Vendor import of clang trunk r321017:vendor/clang/clang-trunk-r321017

https://llvm.org/svn/llvm-project/cfe/trunk@321017

25 files changed, 2288 insertions, 1088 deletions

diff --git a/lib/Format/BreakableToken.cpp b/lib/Format/BreakableToken.cpp
index 3c9df62f80dc..4735ab3564f0 100644
--- a/lib/Format/BreakableToken.cpp
+++ b/lib/Format/BreakableToken.cpp
@@ -40,9 +40,15 @@ static bool IsBlank(char C) {
   }
 }
 
-static StringRef getLineCommentIndentPrefix(StringRef Comment) {
-  static const char *const KnownPrefixes[] = {
-      "///<", "//!<", "///", "//", "//!"};
+static StringRef getLineCommentIndentPrefix(StringRef Comment,
+                                            const FormatStyle &Style) {
+  static const char *const KnownCStylePrefixes[] = {"///<", "//!<", "///", "//",
+                                                    "//!"};
+  static const char *const KnownTextProtoPrefixes[] = {"//", "#"};
+  ArrayRef<const char *> KnownPrefixes(KnownCStylePrefixes);
+  if (Style.Language == FormatStyle::LK_TextProto)
+    KnownPrefixes = KnownTextProtoPrefixes;
+
   StringRef LongestPrefix;
   for (StringRef KnownPrefix : KnownPrefixes) {
     if (Comment.startswith(KnownPrefix)) {
@@ -61,6 +67,8 @@ static BreakableToken::Split getCommentSplit(StringRef Text,
                                              unsigned ColumnLimit,
                                              unsigned TabWidth,
                                              encoding::Encoding Encoding) {
+  DEBUG(llvm::dbgs() << "Comment split: \"" << Text << ", " << ColumnLimit
+                     << "\", Content start: " << ContentStartColumn << "\n");
   if (ColumnLimit <= ContentStartColumn + 1)
     return BreakableToken::Split(StringRef::npos, 0);
 
@@ -165,7 +173,7 @@ bool switchesFormatting(const FormatToken &Token) {
 }
 
 unsigned
-BreakableToken::getLineLengthAfterCompression(unsigned RemainingTokenColumns,
+BreakableToken::getLengthAfterCompression(unsigned RemainingTokenColumns,
                                               Split Split) const {
   // Example: consider the content
   // lala  lala
@@ -175,58 +183,64 @@ BreakableToken::getLineLengthAfterCompression(unsigned RemainingTokenColumns,
   // We compute the number of columns when the split is compressed into a single
   // space, like:
   // lala lala
+  //
+  // FIXME: Correctly measure the length of whitespace in Split.second so it
+  // works with tabs.
   return RemainingTokenColumns + 1 - Split.second;
 }
 
-unsigned BreakableSingleLineToken::getLineCount() const { return 1; }
+unsigned BreakableStringLiteral::getLineCount() const { return 1; }
+
+unsigned BreakableStringLiteral::getRangeLength(unsigned LineIndex,
+                                                unsigned Offset,
+                                                StringRef::size_type Length,
+                                                unsigned StartColumn) const {
+  llvm_unreachable("Getting the length of a part of the string literal "
+                   "indicates that the code tries to reflow it.");
+}
+
+unsigned
+BreakableStringLiteral::getRemainingLength(unsigned LineIndex, unsigned Offset,
+                                           unsigned StartColumn) const {
+  return UnbreakableTailLength + Postfix.size() +
+         encoding::columnWidthWithTabs(Line.substr(Offset, StringRef::npos),
+                                       StartColumn, Style.TabWidth, Encoding);
+}
 
-unsigned BreakableSingleLineToken::getLineLengthAfterSplit(
-    unsigned LineIndex, unsigned TailOffset,
-    StringRef::size_type Length) const {
-  return StartColumn + Prefix.size() + Postfix.size() +
-         encoding::columnWidthWithTabs(Line.substr(TailOffset, Length),
-                                       StartColumn + Prefix.size(),
-                                       Style.TabWidth, Encoding);
+unsigned BreakableStringLiteral::getContentStartColumn(unsigned LineIndex,
+                                                       bool Break) const {
+  return StartColumn + Prefix.size();
 }
 
-BreakableSingleLineToken::BreakableSingleLineToken(
+BreakableStringLiteral::BreakableStringLiteral(
     const FormatToken &Tok, unsigned StartColumn, StringRef Prefix,
     StringRef Postfix, bool InPPDirective, encoding::Encoding Encoding,
     const FormatStyle &Style)
     : BreakableToken(Tok, InPPDirective, Encoding, Style),
-      StartColumn(StartColumn), Prefix(Prefix), Postfix(Postfix) {
+      StartColumn(StartColumn), Prefix(Prefix), Postfix(Postfix),
+      UnbreakableTailLength(Tok.UnbreakableTailLength) {
   assert(Tok.TokenText.startswith(Prefix) && Tok.TokenText.endswith(Postfix));
   Line = Tok.TokenText.substr(
       Prefix.size(), Tok.TokenText.size() - Prefix.size() - Postfix.size());
 }
 
-BreakableStringLiteral::BreakableStringLiteral(
-    const FormatToken &Tok, unsigned StartColumn, StringRef Prefix,
-    StringRef Postfix, bool InPPDirective, encoding::Encoding Encoding,
-    const FormatStyle &Style)
-    : BreakableSingleLineToken(Tok, StartColumn, Prefix, Postfix, InPPDirective,
-                               Encoding, Style) {}
-
-BreakableToken::Split
-BreakableStringLiteral::getSplit(unsigned LineIndex, unsigned TailOffset,
-                                 unsigned ColumnLimit,
-                                 llvm::Regex &CommentPragmasRegex) const {
-  return getStringSplit(Line.substr(TailOffset),
-                        StartColumn + Prefix.size() + Postfix.size(),
-                        ColumnLimit, Style.TabWidth, Encoding);
+BreakableToken::Split BreakableStringLiteral::getSplit(
+    unsigned LineIndex, unsigned TailOffset, unsigned ColumnLimit,
+    unsigned ContentStartColumn, llvm::Regex &CommentPragmasRegex) const {
+  return getStringSplit(Line.substr(TailOffset), ContentStartColumn,
+                        ColumnLimit - Postfix.size(), Style.TabWidth, Encoding);
 }
 
 void BreakableStringLiteral::insertBreak(unsigned LineIndex,
                                          unsigned TailOffset, Split Split,
-                                         WhitespaceManager &Whitespaces) {
+                                         WhitespaceManager &Whitespaces) const {
   Whitespaces.replaceWhitespaceInToken(
       Tok, Prefix.size() + TailOffset + Split.first, Split.second, Postfix,
       Prefix, InPPDirective, 1, StartColumn);
 }
 
 BreakableComment::BreakableComment(const FormatToken &Token,
-                                   unsigned StartColumn,
-                                   bool InPPDirective,
+                                   unsigned StartColumn, bool InPPDirective,
                                    encoding::Encoding Encoding,
                                    const FormatStyle &Style)
     : BreakableToken(Token, InPPDirective, Encoding, Style),
@@ -236,19 +250,19 @@ unsigned BreakableComment::getLineCount() const { return Lines.size(); }
 
 BreakableToken::Split
 BreakableComment::getSplit(unsigned LineIndex, unsigned TailOffset,
-                           unsigned ColumnLimit,
+                           unsigned ColumnLimit, unsigned ContentStartColumn,
                            llvm::Regex &CommentPragmasRegex) const {
   // Don't break lines matching the comment pragmas regex.
   if (CommentPragmasRegex.match(Content[LineIndex]))
     return Split(StringRef::npos, 0);
   return getCommentSplit(Content[LineIndex].substr(TailOffset),
-                         getContentStartColumn(LineIndex, TailOffset),
-                         ColumnLimit, Style.TabWidth, Encoding);
+                         ContentStartColumn, ColumnLimit, Style.TabWidth,
+                         Encoding);
 }
 
-void BreakableComment::compressWhitespace(unsigned LineIndex,
-                                          unsigned TailOffset, Split Split,
-                                          WhitespaceManager &Whitespaces) {
+void BreakableComment::compressWhitespace(
+    unsigned LineIndex, unsigned TailOffset, Split Split,
+    WhitespaceManager &Whitespaces) const {
   StringRef Text = Content[LineIndex].substr(TailOffset);
   // Text is relative to the content line, but Whitespaces operates relative to
   // the start of the corresponding token, so compute the start of the Split
@@ -262,44 +276,6 @@ void BreakableComment::compressWhitespace(unsigned LineIndex,
       /*InPPDirective=*/false, /*Newlines=*/0, /*Spaces=*/1);
 }
 
-BreakableToken::Split
-BreakableComment::getReflowSplit(StringRef Text, StringRef ReflowPrefix,
-                                 unsigned PreviousEndColumn,
-                                 unsigned ColumnLimit) const {
-  unsigned ReflowStartColumn = PreviousEndColumn + ReflowPrefix.size();
-  StringRef TrimmedText = Text.rtrim(Blanks);
-  // This is the width of the resulting line in case the full line of Text gets
-  // reflown up starting at ReflowStartColumn.
-  unsigned FullWidth = ReflowStartColumn + encoding::columnWidthWithTabs(
-                                               TrimmedText, ReflowStartColumn,
-                                               Style.TabWidth, Encoding);
-  // If the full line fits up, we return a reflow split after it,
-  // otherwise we compute the largest piece of text that fits after
-  // ReflowStartColumn.
-  Split ReflowSplit =
-      FullWidth <= ColumnLimit
-          ? Split(TrimmedText.size(), Text.size() - TrimmedText.size())
-          : getCommentSplit(Text, ReflowStartColumn, ColumnLimit,
-                            Style.TabWidth, Encoding);
-
-  // We need to be extra careful here, because while it's OK to keep a long line
-  // if it can't be broken into smaller pieces (like when the first word of a
-  // long line is longer than the column limit), it's not OK to reflow that long
-  // word up. So we recompute the size of the previous line after reflowing and
-  // only return the reflow split if that's under the line limit.
-  if (ReflowSplit.first != StringRef::npos &&
-      // Check if the width of the newly reflown line is under the limit.
-      PreviousEndColumn + ReflowPrefix.size() +
-              encoding::columnWidthWithTabs(Text.substr(0, ReflowSplit.first),
-                                            PreviousEndColumn +
-                                                ReflowPrefix.size(),
-                                            Style.TabWidth, Encoding) <=
-          ColumnLimit) {
-    return ReflowSplit;
-  }
-  return Split(StringRef::npos, 0);
-}
-
 const FormatToken &BreakableComment::tokenAt(unsigned LineIndex) const {
   return Tokens[LineIndex] ? *Tokens[LineIndex] : Tok;
 }
@@ -309,7 +285,7 @@ static bool mayReflowContent(StringRef Content) {
   // Lines starting with '@' commonly have special meaning.
   // Lines starting with '-', '-#', '+' or '*' are bulleted/numbered lists.
   static const SmallVector<StringRef, 8> kSpecialMeaningPrefixes = {
-      "@", "TODO", "FIXME", "XXX", "-# ", "- ", "+ ", "* " };
+      "@", "TODO", "FIXME", "XXX", "-# ", "- ", "+ ", "* "};
   bool hasSpecialMeaningPrefix = false;
   for (StringRef Prefix : kSpecialMeaningPrefixes) {
     if (Content.startswith(Prefix)) {
@@ -322,8 +298,8 @@ static bool mayReflowContent(StringRef Content) {
   // To avoid issues if a line starts with a number which is actually the end
   // of a previous line, we only consider numbers with up to 2 digits.
   static llvm::Regex kNumberedListRegexp = llvm::Regex("^[1-9][0-9]?\\. ");
-  hasSpecialMeaningPrefix = hasSpecialMeaningPrefix ||
-                            kNumberedListRegexp.match(Content);
+  hasSpecialMeaningPrefix =
+      hasSpecialMeaningPrefix || kNumberedListRegexp.match(Content);
 
   // Simple heuristic for what to reflow: content should contain at least two
   // characters and either the first or second character must be
@@ -339,7 +315,9 @@ BreakableBlockComment::BreakableBlockComment(
     const FormatToken &Token, unsigned StartColumn,
     unsigned OriginalStartColumn, bool FirstInLine, bool InPPDirective,
     encoding::Encoding Encoding, const FormatStyle &Style)
-    : BreakableComment(Token, StartColumn, InPPDirective, Encoding, Style) {
+    : BreakableComment(Token, StartColumn, InPPDirective, Encoding, Style),
+      DelimitersOnNewline(false),
+      UnbreakableTailLength(Token.UnbreakableTailLength) {
   assert(Tok.is(TT_BlockComment) &&
          "block comment section must start with a block comment");
 
@@ -384,8 +362,7 @@ BreakableBlockComment::BreakableBlockComment(
     // If the last line is empty, the closing "*/" will have a star.
     if (i + 1 == e && Content[i].empty())
       break;
-    if (!Content[i].empty() && i + 1 != e &&
-        Decoration.startswith(Content[i]))
+    if (!Content[i].empty() && i + 1 != e && Decoration.startswith(Content[i]))
       continue;
     while (!Content[i].startswith(Decoration))
       Decoration = Decoration.substr(0, Decoration.size() - 1);
@@ -427,11 +404,30 @@ BreakableBlockComment::BreakableBlockComment(
       IndentAtLineBreak =
           std::min<int>(IndentAtLineBreak, std::max(0, ContentColumn[i]));
   }
-  IndentAtLineBreak =
-      std::max<unsigned>(IndentAtLineBreak, Decoration.size());
+  IndentAtLineBreak = std::max<unsigned>(IndentAtLineBreak, Decoration.size());
+
+  // Detect a multiline jsdoc comment and set DelimitersOnNewline in that case.
+  if (Style.Language == FormatStyle::LK_JavaScript ||
+      Style.Language == FormatStyle::LK_Java) {
+    if ((Lines[0] == "*" || Lines[0].startswith("* ")) && Lines.size() > 1) {
+      // This is a multiline jsdoc comment.
+      DelimitersOnNewline = true;
+    } else if (Lines[0].startswith("* ") && Lines.size() == 1) {
+      // Detect a long single-line comment, like:
+      // /** long long long */
+      // Below, '2' is the width of '*/'.
+      unsigned EndColumn =
+          ContentColumn[0] +
+          encoding::columnWidthWithTabs(Lines[0], ContentColumn[0],
+                                        Style.TabWidth, Encoding) +
+          2;
+      DelimitersOnNewline = EndColumn > Style.ColumnLimit;
+    }
+  }
 
   DEBUG({
     llvm::dbgs() << "IndentAtLineBreak " << IndentAtLineBreak << "\n";
+    llvm::dbgs() << "DelimitersOnNewline " << DelimitersOnNewline << "\n";
     for (size_t i = 0; i < Lines.size(); ++i) {
       llvm::dbgs() << i << " |" << Content[i] << "| "
                    << "CC=" << ContentColumn[i] << "| "
@@ -477,30 +473,45 @@ void BreakableBlockComment::adjustWhitespace(unsigned LineIndex,
       IndentDelta;
 }
 
-unsigned BreakableBlockComment::getLineLengthAfterSplit(
-    unsigned LineIndex, unsigned TailOffset,
-    StringRef::size_type Length) const {
-  unsigned ContentStartColumn = getContentStartColumn(LineIndex, TailOffset);
+unsigned BreakableBlockComment::getRangeLength(unsigned LineIndex,
+                                               unsigned Offset,
+                                               StringRef::size_type Length,
+                                               unsigned StartColumn) const {
   unsigned LineLength =
-      ContentStartColumn + encoding::columnWidthWithTabs(
-                               Content[LineIndex].substr(TailOffset, Length),
-                               ContentStartColumn, Style.TabWidth, Encoding);
+      encoding::columnWidthWithTabs(Content[LineIndex].substr(Offset, Length),
+                                    StartColumn, Style.TabWidth, Encoding);
+  // FIXME: This should go into getRemainingLength instead, but we currently
+  // break tests when putting it there. Investigate how to fix those tests.
   // The last line gets a "*/" postfix.
   if (LineIndex + 1 == Lines.size()) {
     LineLength += 2;
     // We never need a decoration when breaking just the trailing "*/" postfix.
     // Note that checking that Length == 0 is not enough, since Length could
     // also be StringRef::npos.
-    if (Content[LineIndex].substr(TailOffset, Length).empty()) {
+    if (Content[LineIndex].substr(Offset, StringRef::npos).empty()) {
       LineLength -= Decoration.size();
     }
   }
   return LineLength;
 }
 
+unsigned BreakableBlockComment::getRemainingLength(unsigned LineIndex,
+                                                   unsigned Offset,
+                                                   unsigned StartColumn) const {
+  return UnbreakableTailLength +
+         getRangeLength(LineIndex, Offset, StringRef::npos, StartColumn);
+}
+
+unsigned BreakableBlockComment::getContentStartColumn(unsigned LineIndex,
+                                                      bool Break) const {
+  if (Break)
+    return IndentAtLineBreak;
+  return std::max(0, ContentColumn[LineIndex]);
+}
+
 void BreakableBlockComment::insertBreak(unsigned LineIndex, unsigned TailOffset,
                                         Split Split,
-                                        WhitespaceManager &Whitespaces) {
+                                        WhitespaceManager &Whitespaces) const {
   StringRef Text = Content[LineIndex].substr(TailOffset);
   StringRef Prefix = Decoration;
   // We need this to account for the case when we have a decoration "* " for all
@@ -526,97 +537,55 @@ void BreakableBlockComment::insertBreak(unsigned LineIndex, unsigned TailOffset,
       /*Spaces=*/LocalIndentAtLineBreak - Prefix.size());
 }
 
-BreakableToken::Split BreakableBlockComment::getSplitBefore(
-    unsigned LineIndex,
-    unsigned PreviousEndColumn,
-    unsigned ColumnLimit,
-    llvm::Regex &CommentPragmasRegex) const {
+BreakableToken::Split
+BreakableBlockComment::getReflowSplit(unsigned LineIndex,
+                                      llvm::Regex &CommentPragmasRegex) const {
   if (!mayReflow(LineIndex, CommentPragmasRegex))
     return Split(StringRef::npos, 0);
-  StringRef TrimmedContent = Content[LineIndex].ltrim(Blanks);
-  return getReflowSplit(TrimmedContent, ReflowPrefix, PreviousEndColumn,
-                        ColumnLimit);
-}
-
-unsigned BreakableBlockComment::getReflownColumn(
-    StringRef Content,
-    unsigned LineIndex,
-    unsigned PreviousEndColumn) const {
-    unsigned StartColumn = PreviousEndColumn + ReflowPrefix.size();
-    // If this is the last line, it will carry around its '*/' postfix.
-    unsigned PostfixLength = (LineIndex + 1 == Lines.size() ? 2 : 0);
-    // The line is composed of previous text, reflow prefix, reflown text and
-    // postfix.
-    unsigned ReflownColumn =
-        StartColumn + encoding::columnWidthWithTabs(Content, StartColumn,
-                                                    Style.TabWidth, Encoding) +
-        PostfixLength;
-    return ReflownColumn;
-}
-
-unsigned BreakableBlockComment::getLineLengthAfterSplitBefore(
-    unsigned LineIndex, unsigned TailOffset,
-    unsigned PreviousEndColumn,
-    unsigned ColumnLimit,
-    Split SplitBefore) const {
-  if (SplitBefore.first == StringRef::npos ||
-      // Block comment line contents contain the trailing whitespace after the
-      // decoration, so the need of left trim. Note that this behavior is
-      // consistent with the breaking of block comments where the indentation of
-      // a broken line is uniform across all the lines of the block comment.
-      SplitBefore.first + SplitBefore.second <
-          Content[LineIndex].ltrim().size()) {
-    // A piece of line, not the whole, gets reflown.
-    return getLineLengthAfterSplit(LineIndex, TailOffset, StringRef::npos);
-  } else {
-    // The whole line gets reflown, need to check if we need to insert a break
-    // for the postfix or not.
-    StringRef TrimmedContent = Content[LineIndex].ltrim(Blanks);
-    unsigned ReflownColumn =
-        getReflownColumn(TrimmedContent, LineIndex, PreviousEndColumn);
-    if (ReflownColumn <= ColumnLimit) {
-      return ReflownColumn;
-    }
-    return getLineLengthAfterSplit(LineIndex, TailOffset, StringRef::npos);
-  }
+
+  size_t Trimmed = Content[LineIndex].find_first_not_of(Blanks);
+  return Split(0, Trimmed != StringRef::npos ? Trimmed : 0);
+}
+
+bool BreakableBlockComment::introducesBreakBeforeToken() const {
+  // A break is introduced when we want delimiters on newline.
+  return DelimitersOnNewline &&
+         Lines[0].substr(1).find_first_not_of(Blanks) != StringRef::npos;
 }
-void BreakableBlockComment::replaceWhitespaceBefore(
-    unsigned LineIndex, unsigned PreviousEndColumn, unsigned ColumnLimit,
-    Split SplitBefore, WhitespaceManager &Whitespaces) {
-  if (LineIndex == 0) return;
+
+void BreakableBlockComment::reflow(unsigned LineIndex,
+                                   WhitespaceManager &Whitespaces) const {
   StringRef TrimmedContent = Content[LineIndex].ltrim(Blanks);
-  if (SplitBefore.first != StringRef::npos) {
-    // Here we need to reflow.
-    assert(Tokens[LineIndex - 1] == Tokens[LineIndex] &&
-           "Reflowing whitespace within a token");
-    // This is the offset of the end of the last line relative to the start of
-    // the token text in the token.
-    unsigned WhitespaceOffsetInToken = Content[LineIndex - 1].data() +
-        Content[LineIndex - 1].size() -
-        tokenAt(LineIndex).TokenText.data();
-    unsigned WhitespaceLength = TrimmedContent.data() -
-        tokenAt(LineIndex).TokenText.data() -
-        WhitespaceOffsetInToken;
-    Whitespaces.replaceWhitespaceInToken(
-        tokenAt(LineIndex), WhitespaceOffsetInToken,
-        /*ReplaceChars=*/WhitespaceLength, /*PreviousPostfix=*/"",
-        /*CurrentPrefix=*/ReflowPrefix, InPPDirective, /*Newlines=*/0,
-        /*Spaces=*/0);
-    // Check if we need to also insert a break at the whitespace range.
-    // For this we first adapt the reflow split relative to the beginning of the
-    // content.
-    // Note that we don't need a penalty for this break, since it doesn't change
-    // the total number of lines.
-    Split BreakSplit = SplitBefore;
-    BreakSplit.first += TrimmedContent.data() - Content[LineIndex].data();
-    unsigned ReflownColumn =
-        getReflownColumn(TrimmedContent, LineIndex, PreviousEndColumn);
-    if (ReflownColumn > ColumnLimit) {
-      insertBreak(LineIndex, 0, BreakSplit, Whitespaces);
+  // Here we need to reflow.
+  assert(Tokens[LineIndex - 1] == Tokens[LineIndex] &&
+         "Reflowing whitespace within a token");
+  // This is the offset of the end of the last line relative to the start of
+  // the token text in the token.
+  unsigned WhitespaceOffsetInToken = Content[LineIndex - 1].data() +
+                                     Content[LineIndex - 1].size() -
+                                     tokenAt(LineIndex).TokenText.data();
+  unsigned WhitespaceLength = TrimmedContent.data() -
+                              tokenAt(LineIndex).TokenText.data() -
+                              WhitespaceOffsetInToken;
+  Whitespaces.replaceWhitespaceInToken(
+      tokenAt(LineIndex), WhitespaceOffsetInToken,
+      /*ReplaceChars=*/WhitespaceLength, /*PreviousPostfix=*/"",
+      /*CurrentPrefix=*/ReflowPrefix, InPPDirective, /*Newlines=*/0,
+      /*Spaces=*/0);
+}
+
+void BreakableBlockComment::adaptStartOfLine(
+    unsigned LineIndex, WhitespaceManager &Whitespaces) const {
+  if (LineIndex == 0) {
+    if (DelimitersOnNewline) {
+      // Since we're breaking at index 1 below, the break position and the
+      // break length are the same.
+      size_t BreakLength = Lines[0].substr(1).find_first_not_of(Blanks);
+      if (BreakLength != StringRef::npos)
+        insertBreak(LineIndex, 0, Split(1, BreakLength), Whitespaces);
     }
     return;
   }
-
   // Here no reflow with the previous line will happen.
   // Fix the decoration of the line at LineIndex.
   StringRef Prefix = Decoration;
@@ -651,6 +620,20 @@ void BreakableBlockComment::replaceWhitespaceBefore(
       InPPDirective, /*Newlines=*/1, ContentColumn[LineIndex] - Prefix.size());
 }
 
+BreakableToken::Split
+BreakableBlockComment::getSplitAfterLastLine(unsigned TailOffset) const {
+  if (DelimitersOnNewline) {
+    // Replace the trailing whitespace of the last line with a newline.
+    // In case the last line is empty, the ending '*/' is already on its own
+    // line.
+    StringRef Line = Content.back().substr(TailOffset);
+    StringRef TrimmedLine = Line.rtrim(Blanks);
+    if (!TrimmedLine.empty())
+      return Split(TrimmedLine.size(), Line.size() - TrimmedLine.size());
+  }
+  return Split(StringRef::npos, 0);
+}
+
 bool BreakableBlockComment::mayReflow(unsigned LineIndex,
                                       llvm::Regex &CommentPragmasRegex) const {
   // Content[LineIndex] may exclude the indent after the '*' decoration. In that
@@ -664,15 +647,6 @@ bool BreakableBlockComment::mayReflow(unsigned LineIndex,
          !switchesFormatting(tokenAt(LineIndex));
 }
 
-unsigned
-BreakableBlockComment::getContentStartColumn(unsigned LineIndex,
-                                             unsigned TailOffset) const {
-  // If we break, we always break at the predefined indent.
-  if (TailOffset != 0)
-    return IndentAtLineBreak;
-  return std::max(0, ContentColumn[LineIndex]);
-}
-
 BreakableLineCommentSection::BreakableLineCommentSection(
     const FormatToken &Token, unsigned StartColumn,
     unsigned OriginalStartColumn, bool FirstInLine, bool InPPDirective,
@@ -686,7 +660,8 @@ BreakableLineCommentSection::BreakableLineCommentSection(
        CurrentTok = CurrentTok->Next) {
     LastLineTok = LineTok;
     StringRef TokenText(CurrentTok->TokenText);
-    assert(TokenText.startswith("//"));
+    assert((TokenText.startswith("//") || TokenText.startswith("#")) &&
+           "unsupported line comment prefix, '//' and '#' are supported");
     size_t FirstLineIndex = Lines.size();
     TokenText.split(Lines, "\n");
     Content.resize(Lines.size());
@@ -696,11 +671,13 @@ BreakableLineCommentSection::BreakableLineCommentSection(
     Prefix.resize(Lines.size());
     OriginalPrefix.resize(Lines.size());
     for (size_t i = FirstLineIndex, e = Lines.size(); i < e; ++i) {
+      Lines[i] = Lines[i].ltrim(Blanks);
       // We need to trim the blanks in case this is not the first line in a
       // multiline comment. Then the indent is included in Lines[i].
       StringRef IndentPrefix =
-          getLineCommentIndentPrefix(Lines[i].ltrim(Blanks));
-      assert(IndentPrefix.startswith("//"));
+          getLineCommentIndentPrefix(Lines[i].ltrim(Blanks), Style);
+      assert((TokenText.startswith("//") || TokenText.startswith("#")) &&
+             "unsupported line comment prefix, '//' and '#' are supported");
       OriginalPrefix[i] = Prefix[i] = IndentPrefix;
       if (Lines[i].size() > Prefix[i].size() &&
           isAlphanumeric(Lines[i][Prefix[i].size()])) {
@@ -714,22 +691,20 @@ BreakableLineCommentSection::BreakableLineCommentSection(
           Prefix[i] = "///< ";
         else if (Prefix[i] == "//!<")
           Prefix[i] = "//!< ";
+        else if (Prefix[i] == "#" &&
+                 Style.Language == FormatStyle::LK_TextProto)
+          Prefix[i] = "# ";
       }
 
       Tokens[i] = LineTok;
       Content[i] = Lines[i].substr(IndentPrefix.size());
       OriginalContentColumn[i] =
-          StartColumn +
-          encoding::columnWidthWithTabs(OriginalPrefix[i],
-                                        StartColumn,
-                                        Style.TabWidth,
-                                        Encoding);
+          StartColumn + encoding::columnWidthWithTabs(OriginalPrefix[i],
+                                                      StartColumn,
+                                                      Style.TabWidth, Encoding);
       ContentColumn[i] =
-          StartColumn +
-          encoding::columnWidthWithTabs(Prefix[i],
-                                        StartColumn,
-                                        Style.TabWidth,
-                                        Encoding);
+          StartColumn + encoding::columnWidthWithTabs(Prefix[i], StartColumn,
+                                                      Style.TabWidth, Encoding);
 
       // Calculate the end of the non-whitespace text in this line.
       size_t EndOfLine = Content[i].find_last_not_of(Blanks);
@@ -760,20 +735,25 @@ BreakableLineCommentSection::BreakableLineCommentSection(
   }
 }
 
-unsigned BreakableLineCommentSection::getLineLengthAfterSplit(
-    unsigned LineIndex, unsigned TailOffset,
-    StringRef::size_type Length) const {
-  unsigned ContentStartColumn =
-      (TailOffset == 0 ? ContentColumn[LineIndex]
-                       : OriginalContentColumn[LineIndex]);
-  return ContentStartColumn + encoding::columnWidthWithTabs(
-                                  Content[LineIndex].substr(TailOffset, Length),
-                                  ContentStartColumn, Style.TabWidth, Encoding);
+unsigned
+BreakableLineCommentSection::getRangeLength(unsigned LineIndex, unsigned Offset,
+                                            StringRef::size_type Length,
+                                            unsigned StartColumn) const {
+  return encoding::columnWidthWithTabs(
+      Content[LineIndex].substr(Offset, Length), StartColumn, Style.TabWidth,
+      Encoding);
+}
+
+unsigned BreakableLineCommentSection::getContentStartColumn(unsigned LineIndex,
+                                                            bool Break) const {
+  if (Break)
+    return OriginalContentColumn[LineIndex];
+  return ContentColumn[LineIndex];
 }
 
-void BreakableLineCommentSection::insertBreak(unsigned LineIndex,
-                                              unsigned TailOffset, Split Split,
-                                              WhitespaceManager &Whitespaces) {
+void BreakableLineCommentSection::insertBreak(
+    unsigned LineIndex, unsigned TailOffset, Split Split,
+    WhitespaceManager &Whitespaces) const {
   StringRef Text = Content[LineIndex].substr(TailOffset);
   // Compute the offset of the split relative to the beginning of the token
   // text.
@@ -792,37 +772,42 @@ void BreakableLineCommentSection::insertBreak(unsigned LineIndex,
       /*Spaces=*/IndentAtLineBreak - Prefix[LineIndex].size());
 }
 
-BreakableComment::Split BreakableLineCommentSection::getSplitBefore(
-    unsigned LineIndex, unsigned PreviousEndColumn, unsigned ColumnLimit,
-    llvm::Regex &CommentPragmasRegex) const {
+BreakableComment::Split BreakableLineCommentSection::getReflowSplit(
+    unsigned LineIndex, llvm::Regex &CommentPragmasRegex) const {
   if (!mayReflow(LineIndex, CommentPragmasRegex))
     return Split(StringRef::npos, 0);
-  return getReflowSplit(Content[LineIndex], ReflowPrefix, PreviousEndColumn,
-                        ColumnLimit);
-}
-
-unsigned BreakableLineCommentSection::getLineLengthAfterSplitBefore(
-    unsigned LineIndex, unsigned TailOffset,
-    unsigned PreviousEndColumn,
-    unsigned ColumnLimit,
-    Split SplitBefore) const {
-  if (SplitBefore.first == StringRef::npos ||
-      SplitBefore.first + SplitBefore.second < Content[LineIndex].size()) {
-    // A piece of line, not the whole line, gets reflown.
-    return getLineLengthAfterSplit(LineIndex, TailOffset, StringRef::npos);
-  } else {
-    // The whole line gets reflown.
-    unsigned StartColumn = PreviousEndColumn + ReflowPrefix.size();
-    return StartColumn + encoding::columnWidthWithTabs(Content[LineIndex],
-                                                       StartColumn,
-                                                       Style.TabWidth,
-                                                       Encoding);
-  }
-}
 
-void BreakableLineCommentSection::replaceWhitespaceBefore(
-    unsigned LineIndex, unsigned PreviousEndColumn, unsigned ColumnLimit,
-    Split SplitBefore, WhitespaceManager &Whitespaces) {
+  size_t Trimmed = Content[LineIndex].find_first_not_of(Blanks);
+
+  // In a line comment section each line is a separate token; thus, after a
+  // split we replace all whitespace before the current line comment token
+  // (which does not need to be included in the split), plus the start of the
+  // line up to where the content starts.
+  return Split(0, Trimmed != StringRef::npos ? Trimmed : 0);
+}
+
+void BreakableLineCommentSection::reflow(unsigned LineIndex,
+                                         WhitespaceManager &Whitespaces) const {
+  // Reflow happens between tokens. Replace the whitespace between the
+  // tokens by the empty string.
+  Whitespaces.replaceWhitespace(
+      *Tokens[LineIndex], /*Newlines=*/0, /*Spaces=*/0,
+      /*StartOfTokenColumn=*/StartColumn, /*InPPDirective=*/false);
+  // Replace the indent and prefix of the token with the reflow prefix.
+  unsigned WhitespaceLength =
+      Content[LineIndex].data() - tokenAt(LineIndex).TokenText.data();
+  Whitespaces.replaceWhitespaceInToken(*Tokens[LineIndex],
+                                       /*Offset=*/0,
+                                       /*ReplaceChars=*/WhitespaceLength,
+                                       /*PreviousPostfix=*/"",
+                                       /*CurrentPrefix=*/ReflowPrefix,
+                                       /*InPPDirective=*/false,
+                                       /*Newlines=*/0,
+                                       /*Spaces=*/0);
+}
+
+void BreakableLineCommentSection::adaptStartOfLine(
+    unsigned LineIndex, WhitespaceManager &Whitespaces) const {
   // If this is the first line of a token, we need to inform Whitespace Manager
   // about it: either adapt the whitespace range preceding it, or mark it as an
   // untouchable token.
@@ -830,44 +815,25 @@ void BreakableLineCommentSection::replaceWhitespaceBefore(
   // // line 1 \
   // // line 2
   if (LineIndex > 0 && Tokens[LineIndex] != Tokens[LineIndex - 1]) {
-    if (SplitBefore.first != StringRef::npos) {
-      // Reflow happens between tokens. Replace the whitespace between the
-      // tokens by the empty string.
-      Whitespaces.replaceWhitespace(
-          *Tokens[LineIndex], /*Newlines=*/0, /*Spaces=*/0,
-          /*StartOfTokenColumn=*/StartColumn, /*InPPDirective=*/false);
-      // Replace the indent and prefix of the token with the reflow prefix.
-      unsigned WhitespaceLength =
-          Content[LineIndex].data() - tokenAt(LineIndex).TokenText.data();
-      Whitespaces.replaceWhitespaceInToken(*Tokens[LineIndex],
-                                           /*Offset=*/0,
-                                           /*ReplaceChars=*/WhitespaceLength,
-                                           /*PreviousPostfix=*/"",
-                                           /*CurrentPrefix=*/ReflowPrefix,
-                                           /*InPPDirective=*/false,
-                                           /*Newlines=*/0,
-                                           /*Spaces=*/0);
-    } else {
-      // This is the first line for the current token, but no reflow with the
-      // previous token is necessary. However, we still may need to adjust the
-      // start column. Note that ContentColumn[LineIndex] is the expected
-      // content column after a possible update to the prefix, hence the prefix
-      // length change is included.
-      unsigned LineColumn =
-          ContentColumn[LineIndex] -
-          (Content[LineIndex].data() - Lines[LineIndex].data()) +
-          (OriginalPrefix[LineIndex].size() - Prefix[LineIndex].size());
-
-      // We always want to create a replacement instead of adding an untouchable
-      // token, even if LineColumn is the same as the original column of the
-      // token. This is because WhitespaceManager doesn't align trailing
-      // comments if they are untouchable.
-      Whitespaces.replaceWhitespace(*Tokens[LineIndex],
-                                    /*Newlines=*/1,
-                                    /*Spaces=*/LineColumn,
-                                    /*StartOfTokenColumn=*/LineColumn,
-                                    /*InPPDirective=*/false);
-    }
+    // This is the first line for the current token, but no reflow with the
+    // previous token is necessary. However, we still may need to adjust the
+    // start column. Note that ContentColumn[LineIndex] is the expected
+    // content column after a possible update to the prefix, hence the prefix
+    // length change is included.
+    unsigned LineColumn =
+        ContentColumn[LineIndex] -
+        (Content[LineIndex].data() - Lines[LineIndex].data()) +
+        (OriginalPrefix[LineIndex].size() - Prefix[LineIndex].size());
+
+    // We always want to create a replacement instead of adding an untouchable
+    // token, even if LineColumn is the same as the original column of the
+    // token. This is because WhitespaceManager doesn't align trailing
+    // comments if they are untouchable.
+    Whitespaces.replaceWhitespace(*Tokens[LineIndex],
+                                  /*Newlines=*/1,
+                                  /*Spaces=*/LineColumn,
+                                  /*StartOfTokenColumn=*/LineColumn,
+                                  /*InPPDirective=*/false);
   }
   if (OriginalPrefix[LineIndex] != Prefix[LineIndex]) {
     // Adjust the prefix if necessary.
@@ -880,16 +846,9 @@ void BreakableLineCommentSection::replaceWhitespaceBefore(
         tokenAt(LineIndex), OriginalPrefix[LineIndex].size(), 0, "", "",
         /*InPPDirective=*/false, /*Newlines=*/0, /*Spaces=*/1);
   }
-  // Add a break after a reflow split has been introduced, if necessary.
-  // Note that this break doesn't need to be penalized, since it doesn't change
-  // the number of lines.
-  if (SplitBefore.first != StringRef::npos &&
-      SplitBefore.first + SplitBefore.second < Content[LineIndex].size()) {
-    insertBreak(LineIndex, 0, SplitBefore, Whitespaces);
-  }
 }
 
-void BreakableLineCommentSection::updateNextToken(LineState& State) const {
+void BreakableLineCommentSection::updateNextToken(LineState &State) const {
   if (LastLineTok) {
     State.NextToken = LastLineTok->Next;
   }
@@ -903,20 +862,17 @@ bool BreakableLineCommentSection::mayReflow(
   if (Lines[LineIndex].startswith("//")) {
     IndentContent = Lines[LineIndex].substr(2);
   }
+  // FIXME: Decide whether we want to reflow non-regular indents:
+  // Currently, we only reflow when the OriginalPrefix[LineIndex] matches the
+  // OriginalPrefix[LineIndex-1]. That means we don't reflow
+  // // text that protrudes
+  // //    into text with different indent
+  // We do reflow in that case in block comments.
   return LineIndex > 0 && !CommentPragmasRegex.match(IndentContent) &&
          mayReflowContent(Content[LineIndex]) && !Tok.Finalized &&
          !switchesFormatting(tokenAt(LineIndex)) &&
          OriginalPrefix[LineIndex] == OriginalPrefix[LineIndex - 1];
 }
 
-unsigned
-BreakableLineCommentSection::getContentStartColumn(unsigned LineIndex,
-                                                   unsigned TailOffset) const {
-  if (TailOffset != 0) {
-    return OriginalContentColumn[LineIndex];
-  }
-  return ContentColumn[LineIndex];
-}
-
 } // namespace format
 } // namespace clang
diff --git a/lib/Format/BreakableToken.h b/lib/Format/BreakableToken.h
index e642a538e21c..8ef26ef464da 100644
--- a/lib/Format/BreakableToken.h
+++ b/lib/Format/BreakableToken.h
@@ -33,19 +33,32 @@ bool switchesFormatting(const FormatToken &Token);
 
 struct FormatStyle;
 
-/// \brief Base class for strategies on how to break tokens.
+/// \brief Base class for tokens / ranges of tokens that can allow breaking
+/// within the tokens - for example, to avoid whitespace beyond the column
+/// limit, or to reflow text.
 ///
-/// This is organised around the concept of a \c Split, which is a whitespace
-/// range that signifies a position of the content of a token where a
-/// reformatting might be done. Operating with splits is divided into 3
-/// operations:
+/// Generally, a breakable token consists of logical lines, addressed by a line
+/// index. For example, in a sequence of line comments, each line comment is its
+/// own logical line; similarly, for a block comment, each line in the block
+/// comment is on its own logical line.
+///
+/// There are two methods to compute the layout of the token:
+/// - getRangeLength measures the number of columns needed for a range of text
+///   within a logical line, and
+/// - getContentStartColumn returns the start column at which we want the
+///   content of a logical line to start (potentially after introducing a line
+///   break).
+///
+/// The mechanism to adapt the layout of the breakable token is organised
+/// around the concept of a \c Split, which is a whitespace range that signifies
+/// a position of the content of a token where a reformatting might be done.
+///
+/// Operating with splits is divided into two operations:
 /// - getSplit, for finding a split starting at a position,
-/// - getLineLengthAfterSplit, for calculating the size in columns of the rest
-///   of the content after a split has been used for breaking, and
 /// - insertBreak, for executing the split using a whitespace manager.
 ///
 /// There is a pair of operations that are used to compress a long whitespace
-/// range with a single space if that will bring the line lenght under the
+/// range with a single space if that will bring the line length under the
 /// column limit:
 /// - getLineLengthAfterCompression, for calculating the size in columns of the
 ///   line after a whitespace range has been compressed, and
@@ -56,16 +69,23 @@ struct FormatStyle;
 /// For tokens where the whitespace before each line needs to be also
 /// reformatted, for example for tokens supporting reflow, there are analogous
 /// operations that might be executed before the main line breaking occurs:
-/// - getSplitBefore, for finding a split such that the content preceding it
+/// - getReflowSplit, for finding a split such that the content preceding it
 ///   needs to be specially reflown,
-/// - getLineLengthAfterSplitBefore, for calculating the line length in columns
-///   of the remainder of the content after the beginning of the content has
-///   been reformatted, and
-/// - replaceWhitespaceBefore, for executing the reflow using a whitespace
+/// - reflow, for executing the split using a whitespace manager,
+/// - introducesBreakBefore, for checking if reformatting the beginning
+///   of the content introduces a line break before it,
+/// - adaptStartOfLine, for executing the reflow using a whitespace
 ///   manager.
 ///
-/// FIXME: The interface seems set in stone, so we might want to just pull the
-/// strategy into the class, instead of controlling it from the outside.
+/// For tokens that require the whitespace after the last line to be
+/// reformatted, for example in multiline jsdoc comments that require the
+/// trailing '*/' to be on a line of itself, there are analogous operations
+/// that might be executed after the last line has been reformatted:
+/// - getSplitAfterLastLine, for finding a split after the last line that needs
+///   to be reflown,
+/// - replaceWhitespaceAfterLastLine, for executing the reflow using a
+///   whitespace manager.
+///
 class BreakableToken {
 public:
   /// \brief Contains starting character index and length of split.
@@ -76,73 +96,122 @@ public:
   /// \brief Returns the number of lines in this token in the original code.
   virtual unsigned getLineCount() const = 0;
 
-  /// \brief Returns the number of columns required to format the piece of line
-  /// at \p LineIndex, from byte offset \p TailOffset with length \p Length.
+  /// \brief Returns the number of columns required to format the text in the
+  /// byte range [\p Offset, \p Offset \c + \p Length).
+  ///
+  /// \p Offset is the byte offset from the start of the content of the line
+  ///    at \p LineIndex.
+  ///
+  /// \p StartColumn is the column at which the text starts in the formatted
+  ///    file, needed to compute tab stops correctly.
+  virtual unsigned getRangeLength(unsigned LineIndex, unsigned Offset,
+                                  StringRef::size_type Length,
+                                  unsigned StartColumn) const = 0;
+
+  /// \brief Returns the number of columns required to format the text following
+  /// the byte \p Offset in the line \p LineIndex, including potentially
+  /// unbreakable sequences of tokens following after the end of the token.
+  ///
+  /// \p Offset is the byte offset from the start of the content of the line
+  ///    at \p LineIndex.
+  ///
+  /// \p StartColumn is the column at which the text starts in the formatted
+  ///    file, needed to compute tab stops correctly.
   ///
-  /// Note that previous breaks are not taken into account. \p TailOffset is
-  /// always specified from the start of the (original) line.
-  /// \p Length can be set to StringRef::npos, which means "to the end of line".
-  virtual unsigned
-  getLineLengthAfterSplit(unsigned LineIndex, unsigned TailOffset,
-                          StringRef::size_type Length) const = 0;
+  /// For breakable tokens that never use extra space at the end of a line, this
+  /// is equivalent to getRangeLength with a Length of StringRef::npos.
+  virtual unsigned getRemainingLength(unsigned LineIndex, unsigned Offset,
+                                      unsigned StartColumn) const {
+    return getRangeLength(LineIndex, Offset, StringRef::npos, StartColumn);
+  }
+
+  /// \brief Returns the column at which content in line \p LineIndex starts,
+  /// assuming no reflow.
+  ///
+  /// If \p Break is true, returns the column at which the line should start
+  /// after the line break.
+  /// If \p Break is false, returns the column at which the line itself will
+  /// start.
+  virtual unsigned getContentStartColumn(unsigned LineIndex,
+                                         bool Break) const = 0;
 
   /// \brief Returns a range (offset, length) at which to break the line at
   /// \p LineIndex, if previously broken at \p TailOffset. If possible, do not
-  /// violate \p ColumnLimit.
+  /// violate \p ColumnLimit, assuming the text starting at \p TailOffset in
+  /// the token is formatted starting at ContentStartColumn in the reformatted
+  /// file.
   virtual Split getSplit(unsigned LineIndex, unsigned TailOffset,
-                         unsigned ColumnLimit,
+                         unsigned ColumnLimit, unsigned ContentStartColumn,
                          llvm::Regex &CommentPragmasRegex) const = 0;
 
   /// \brief Emits the previously retrieved \p Split via \p Whitespaces.
   virtual void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
-                           WhitespaceManager &Whitespaces) = 0;
+                           WhitespaceManager &Whitespaces) const = 0;
 
-  /// \brief Returns the number of columns required to format the piece of line
-  /// at \p LineIndex, from byte offset \p TailOffset after the whitespace range
-  /// \p Split has been compressed into a single space.
-  unsigned getLineLengthAfterCompression(unsigned RemainingTokenColumns,
-                                         Split Split) const;
+  /// \brief Returns the number of columns needed to format
+  /// \p RemainingTokenColumns, assuming that Split is within the range measured
+  /// by \p RemainingTokenColumns, and that the whitespace in Split is reduced
+  /// to a single space.
+  unsigned getLengthAfterCompression(unsigned RemainingTokenColumns,
+                                     Split Split) const;
 
   /// \brief Replaces the whitespace range described by \p Split with a single
   /// space.
   virtual void compressWhitespace(unsigned LineIndex, unsigned TailOffset,
                                   Split Split,
-                                  WhitespaceManager &Whitespaces) = 0;
+                                  WhitespaceManager &Whitespaces) const = 0;
 
-  /// \brief Returns a whitespace range (offset, length) of the content at
-  /// \p LineIndex such that the content preceding this range needs to be
-  /// reformatted before any breaks are made to this line.
+  /// \brief Returns whether the token supports reflowing text.
+  virtual bool supportsReflow() const { return false; }
+
+  /// \brief Returns a whitespace range (offset, length) of the content at \p
+  /// LineIndex such that the content of that line is reflown to the end of the
+  /// previous one.
   ///
-  /// \p PreviousEndColumn is the end column of the previous line after
-  /// formatting.
+  /// Returning (StringRef::npos, 0) indicates reflowing is not possible.
   ///
-  /// A result having offset == StringRef::npos means that no piece of the line
-  /// needs to be reformatted before any breaks are made.
-  virtual Split getSplitBefore(unsigned LineIndex, unsigned PreviousEndColumn,
-                               unsigned ColumnLimit,
+  /// The range will include any whitespace preceding the specified line's
+  /// content.
+  ///
+  /// If the split is not contained within one token, for example when reflowing
+  /// line comments, returns (0, <length>).
+  virtual Split getReflowSplit(unsigned LineIndex,
                                llvm::Regex &CommentPragmasRegex) const {
     return Split(StringRef::npos, 0);
   }
 
-  /// \brief Returns the number of columns required to format the piece of line
-  /// at \p LineIndex after the content preceding the whitespace range specified
-  /// \p SplitBefore has been reformatted, but before any breaks are made to
-  /// this line.
-  virtual unsigned getLineLengthAfterSplitBefore(unsigned LineIndex,
-                                                 unsigned TailOffset,
-                                                 unsigned PreviousEndColumn,
-                                                 unsigned ColumnLimit,
-                                                 Split SplitBefore) const {
-    return getLineLengthAfterSplit(LineIndex, TailOffset, StringRef::npos);
+  /// \brief Reflows the current line into the end of the previous one.
+  virtual void reflow(unsigned LineIndex,
+                      WhitespaceManager &Whitespaces) const {}
+
+  /// \brief Returns whether there will be a line break at the start of the
+  /// token.
+  virtual bool introducesBreakBeforeToken() const {
+    return false;
   }
 
   /// \brief Replaces the whitespace between \p LineIndex-1 and \p LineIndex.
-  /// Performs a reformatting of the content at \p LineIndex preceding the
-  /// whitespace range \p SplitBefore.
-  virtual void replaceWhitespaceBefore(unsigned LineIndex,
-                                       unsigned PreviousEndColumn,
-                                       unsigned ColumnLimit, Split SplitBefore,
-                                       WhitespaceManager &Whitespaces) {}
+  virtual void adaptStartOfLine(unsigned LineIndex,
+                                WhitespaceManager &Whitespaces) const {}
+
+  /// \brief Returns a whitespace range (offset, length) of the content at
+  /// the last line that needs to be reformatted after the last line has been
+  /// reformatted.
+  ///
+  /// A result having offset == StringRef::npos means that no reformat is
+  /// necessary.
+  virtual Split getSplitAfterLastLine(unsigned TailOffset) const {
+    return Split(StringRef::npos, 0);
+  }
+
+  /// \brief Replaces the whitespace from \p SplitAfterLastLine on the last line
+  /// after the last line has been formatted by performing a reformatting.
+  void replaceWhitespaceAfterLastLine(unsigned TailOffset,
+                                      Split SplitAfterLastLine,
+                                      WhitespaceManager &Whitespaces) const {
+    insertBreak(getLineCount() - 1, TailOffset, SplitAfterLastLine,
+                Whitespaces);
+  }
 
   /// \brief Updates the next token of \p State to the next token after this
   /// one. This can be used when this token manages a set of underlying tokens
@@ -161,32 +230,7 @@ protected:
   const FormatStyle &Style;
 };
 
-/// \brief Base class for single line tokens that can be broken.
-///
-/// \c getSplit() needs to be implemented by child classes.
-class BreakableSingleLineToken : public BreakableToken {
-public:
-  unsigned getLineCount() const override;
-  unsigned getLineLengthAfterSplit(unsigned LineIndex, unsigned TailOffset,
-                                   StringRef::size_type Length) const override;
-
-protected:
-  BreakableSingleLineToken(const FormatToken &Tok, unsigned StartColumn,
-                           StringRef Prefix, StringRef Postfix,
-                           bool InPPDirective, encoding::Encoding Encoding,
-                           const FormatStyle &Style);
-
-  // The column in which the token starts.
-  unsigned StartColumn;
-  // The prefix a line needs after a break in the token.
-  StringRef Prefix;
-  // The postfix a line needs before introducing a break.
-  StringRef Postfix;
-  // The token text excluding the prefix and postfix.
-  StringRef Line;
-};
-
-class BreakableStringLiteral : public BreakableSingleLineToken {
+class BreakableStringLiteral : public BreakableToken {
 public:
   /// \brief Creates a breakable token for a single line string literal.
   ///
@@ -198,11 +242,32 @@ public:
                          const FormatStyle &Style);
 
   Split getSplit(unsigned LineIndex, unsigned TailOffset, unsigned ColumnLimit,
+                 unsigned ReflowColumn,
                  llvm::Regex &CommentPragmasRegex) const override;
   void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
-                   WhitespaceManager &Whitespaces) override;
+                   WhitespaceManager &Whitespaces) const override;
   void compressWhitespace(unsigned LineIndex, unsigned TailOffset, Split Split,
-                          WhitespaceManager &Whitespaces) override {}
+                          WhitespaceManager &Whitespaces) const override {}
+  unsigned getLineCount() const override;
+  unsigned getRangeLength(unsigned LineIndex, unsigned Offset,
+                          StringRef::size_type Length,
+                          unsigned StartColumn) const override;
+  unsigned getRemainingLength(unsigned LineIndex, unsigned Offset,
+                              unsigned StartColumn) const override;
+  unsigned getContentStartColumn(unsigned LineIndex, bool Break) const override;
+
+protected:
+  // The column in which the token starts.
+  unsigned StartColumn;
+  // The prefix a line needs after a break in the token.
+  StringRef Prefix;
+  // The postfix a line needs before introducing a break.
+  StringRef Postfix;
+  // The token text excluding the prefix and postfix.
+  StringRef Line;
+  // Length of the sequence of tokens after this string literal that cannot
+  // contain line breaks.
+  unsigned UnbreakableTailLength;
 };
 
 class BreakableComment : public BreakableToken {
@@ -216,21 +281,15 @@ protected:
                    const FormatStyle &Style);
 
 public:
+  bool supportsReflow() const override { return true; }
   unsigned getLineCount() const override;
   Split getSplit(unsigned LineIndex, unsigned TailOffset, unsigned ColumnLimit,
+                 unsigned ReflowColumn,
                  llvm::Regex &CommentPragmasRegex) const override;
   void compressWhitespace(unsigned LineIndex, unsigned TailOffset, Split Split,
-                          WhitespaceManager &Whitespaces) override;
+                          WhitespaceManager &Whitespaces) const override;
 
 protected:
-  virtual unsigned getContentStartColumn(unsigned LineIndex,
-                                         unsigned TailOffset) const = 0;
-
-  // Returns a split that divides Text into a left and right parts, such that
-  // the left part is suitable for reflowing after PreviousEndColumn.
-  Split getReflowSplit(StringRef Text, StringRef ReflowPrefix,
-                       unsigned PreviousEndColumn, unsigned ColumnLimit) const;
-
   // Returns the token containing the line at LineIndex.
   const FormatToken &tokenAt(unsigned LineIndex) const;
 
@@ -289,21 +348,23 @@ public:
                         bool InPPDirective, encoding::Encoding Encoding,
                         const FormatStyle &Style);
 
-  unsigned getLineLengthAfterSplit(unsigned LineIndex, unsigned TailOffset,
-                                   StringRef::size_type Length) const override;
+  unsigned getRangeLength(unsigned LineIndex, unsigned Offset,
+                          StringRef::size_type Length,
+                          unsigned StartColumn) const override;
+  unsigned getRemainingLength(unsigned LineIndex, unsigned Offset,
+                              unsigned StartColumn) const override;
+  unsigned getContentStartColumn(unsigned LineIndex, bool Break) const override;
   void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
-                   WhitespaceManager &Whitespaces) override;
-  Split getSplitBefore(unsigned LineIndex, unsigned PreviousEndColumn,
-                       unsigned ColumnLimit,
+                   WhitespaceManager &Whitespaces) const override;
+  Split getReflowSplit(unsigned LineIndex,
                        llvm::Regex &CommentPragmasRegex) const override;
-  unsigned getLineLengthAfterSplitBefore(unsigned LineIndex,
-                                         unsigned TailOffset,
-                                         unsigned PreviousEndColumn,
-                                         unsigned ColumnLimit,
-                                         Split SplitBefore) const override;
-  void replaceWhitespaceBefore(unsigned LineIndex, unsigned PreviousEndColumn,
-                               unsigned ColumnLimit, Split SplitBefore,
-                               WhitespaceManager &Whitespaces) override;
+  void reflow(unsigned LineIndex,
+              WhitespaceManager &Whitespaces) const override;
+  bool introducesBreakBeforeToken() const override;
+  void adaptStartOfLine(unsigned LineIndex,
+                        WhitespaceManager &Whitespaces) const override;
+  Split getSplitAfterLastLine(unsigned TailOffset) const override;
+
   bool mayReflow(unsigned LineIndex,
                  llvm::Regex &CommentPragmasRegex) const override;
 
@@ -318,14 +379,6 @@ private:
   // considered part of the text).
   void adjustWhitespace(unsigned LineIndex, int IndentDelta);
 
-  // Computes the end column if the full Content from LineIndex gets reflown
-  // after PreviousEndColumn.
-  unsigned getReflownColumn(StringRef Content, unsigned LineIndex,
-                            unsigned PreviousEndColumn) const;
-
-  unsigned getContentStartColumn(unsigned LineIndex,
-                                 unsigned TailOffset) const override;
-
   // The column at which the text of a broken line should start.
   // Note that an optional decoration would go before that column.
   // IndentAtLineBreak is a uniform position for all lines in a block comment,
@@ -348,6 +401,14 @@ private:
   // If this block comment has decorations, this is the column of the start of
   // the decorations.
   unsigned DecorationColumn;
+
+  // If true, make sure that the opening '/**' and the closing '*/' ends on a
+  // line of itself. Styles like jsdoc require this for multiline comments.
+  bool DelimitersOnNewline;
+
+  // Length of the sequence of tokens after this string literal that cannot
+  // contain line breaks.
+  unsigned UnbreakableTailLength;
 };
 
 class BreakableLineCommentSection : public BreakableComment {
@@ -357,29 +418,23 @@ public:
                               bool InPPDirective, encoding::Encoding Encoding,
                               const FormatStyle &Style);
 
-  unsigned getLineLengthAfterSplit(unsigned LineIndex, unsigned TailOffset,
-                                   StringRef::size_type Length) const override;
+  unsigned getRangeLength(unsigned LineIndex, unsigned Offset,
+                          StringRef::size_type Length,
+                          unsigned StartColumn) const override;
+  unsigned getContentStartColumn(unsigned LineIndex, bool Break) const override;
   void insertBreak(unsigned LineIndex, unsigned TailOffset, Split Split,
-                   WhitespaceManager &Whitespaces) override;
-  Split getSplitBefore(unsigned LineIndex, unsigned PreviousEndColumn,
-                       unsigned ColumnLimit,
+                   WhitespaceManager &Whitespaces) const override;
+  Split getReflowSplit(unsigned LineIndex,
                        llvm::Regex &CommentPragmasRegex) const override;
-  unsigned getLineLengthAfterSplitBefore(unsigned LineIndex,
-                                         unsigned TailOffset,
-                                         unsigned PreviousEndColumn,
-                                         unsigned ColumnLimit,
-                                         Split SplitBefore) const override;
-  void replaceWhitespaceBefore(unsigned LineIndex, unsigned PreviousEndColumn,
-                               unsigned ColumnLimit, Split SplitBefore,
-                               WhitespaceManager &Whitespaces) override;
+  void reflow(unsigned LineIndex,
+              WhitespaceManager &Whitespaces) const override;
+  void adaptStartOfLine(unsigned LineIndex,
+                        WhitespaceManager &Whitespaces) const override;
   void updateNextToken(LineState &State) const override;
   bool mayReflow(unsigned LineIndex,
                  llvm::Regex &CommentPragmasRegex) const override;
 
 private:
-  unsigned getContentStartColumn(unsigned LineIndex,
-                                 unsigned TailOffset) const override;
-
   // OriginalPrefix[i] contains the original prefix of line i, including
   // trailing whitespace before the start of the content. The indentation
   // preceding the prefix is not included.
diff --git a/lib/Format/ContinuationIndenter.cpp b/lib/Format/ContinuationIndenter.cpp
index 3bf1cd8f7c13..a3d38b244c5c 100644
--- a/lib/Format/ContinuationIndenter.cpp
+++ b/lib/Format/ContinuationIndenter.cpp
@@ -12,8 +12,9 @@
 ///
 //===----------------------------------------------------------------------===//
 
-#include "BreakableToken.h"
 #include "ContinuationIndenter.h"
+#include "BreakableToken.h"
+#include "FormatInternal.h"
 #include "WhitespaceManager.h"
 #include "clang/Basic/OperatorPrecedence.h"
 #include "clang/Basic/SourceManager.h"
@@ -76,6 +77,53 @@ static bool opensProtoMessageField(const FormatToken &LessTok,
            (LessTok.Previous && LessTok.Previous->is(tok::equal))));
 }
 
+// Returns the delimiter of a raw string literal, or None if TokenText is not
+// the text of a raw string literal. The delimiter could be the empty string.
+// For example, the delimiter of R"deli(cont)deli" is deli.
+static llvm::Optional<StringRef> getRawStringDelimiter(StringRef TokenText) {
+  if (TokenText.size() < 5 // The smallest raw string possible is 'R"()"'.
+      || !TokenText.startswith("R\"") || !TokenText.endswith("\""))
+    return None;
+
+  // A raw string starts with 'R"<delimiter>(' and delimiter is ascii and has
+  // size at most 16 by the standard, so the first '(' must be among the first
+  // 19 bytes.
+  size_t LParenPos = TokenText.substr(0, 19).find_first_of('(');
+  if (LParenPos == StringRef::npos)
+    return None;
+  StringRef Delimiter = TokenText.substr(2, LParenPos - 2);
+
+  // Check that the string ends in ')Delimiter"'.
+  size_t RParenPos = TokenText.size() - Delimiter.size() - 2;
+  if (TokenText[RParenPos] != ')')
+    return None;
+  if (!TokenText.substr(RParenPos + 1).startswith(Delimiter))
+    return None;
+  return Delimiter;
+}
+
+RawStringFormatStyleManager::RawStringFormatStyleManager(
+    const FormatStyle &CodeStyle) {
+  for (const auto &RawStringFormat : CodeStyle.RawStringFormats) {
+    FormatStyle Style;
+    if (!getPredefinedStyle(RawStringFormat.BasedOnStyle,
+                            RawStringFormat.Language, &Style)) {
+      Style = getLLVMStyle();
+      Style.Language = RawStringFormat.Language;
+    }
+    Style.ColumnLimit = CodeStyle.ColumnLimit;
+    DelimiterStyle.insert({RawStringFormat.Delimiter, Style});
+  }
+}
+
+llvm::Optional<FormatStyle>
+RawStringFormatStyleManager::get(StringRef Delimiter) const {
+  auto It = DelimiterStyle.find(Delimiter);
+  if (It == DelimiterStyle.end())
+    return None;
+  return It->second;
+}
+
 ContinuationIndenter::ContinuationIndenter(const FormatStyle &Style,
                                            const AdditionalKeywords &Keywords,
                                            const SourceManager &SourceMgr,
@@ -85,20 +133,32 @@ ContinuationIndenter::ContinuationIndenter(const FormatStyle &Style,
     : Style(Style), Keywords(Keywords), SourceMgr(SourceMgr),
       Whitespaces(Whitespaces), Encoding(Encoding),
       BinPackInconclusiveFunctions(BinPackInconclusiveFunctions),
-      CommentPragmasRegex(Style.CommentPragmas) {}
+      CommentPragmasRegex(Style.CommentPragmas), RawStringFormats(Style) {}
 
 LineState ContinuationIndenter::getInitialState(unsigned FirstIndent,
+                                                unsigned FirstStartColumn,
                                                 const AnnotatedLine *Line,
                                                 bool DryRun) {
   LineState State;
   State.FirstIndent = FirstIndent;
-  State.Column = FirstIndent;
+  if (FirstStartColumn && Line->First->NewlinesBefore == 0)
+    State.Column = FirstStartColumn;
+  else
+    State.Column = FirstIndent;
+  // With preprocessor directive indentation, the line starts on column 0
+  // since it's indented after the hash, but FirstIndent is set to the
+  // preprocessor indent.
+  if (Style.IndentPPDirectives == FormatStyle::PPDIS_AfterHash &&
+      (Line->Type == LT_PreprocessorDirective ||
+       Line->Type == LT_ImportStatement))
+    State.Column = 0;
   State.Line = Line;
   State.NextToken = Line->First;
   State.Stack.push_back(ParenState(FirstIndent, FirstIndent,
                                    /*AvoidBinPacking=*/false,
                                    /*NoLineBreak=*/false));
   State.LineContainsContinuedForLoopSection = false;
+  State.NoContinuation = false;
   State.StartOfStringLiteral = 0;
   State.StartOfLineLevel = 0;
   State.LowestLevelOnLine = 0;
@@ -120,9 +180,8 @@ bool ContinuationIndenter::canBreak(const LineState &State) {
   const FormatToken &Current = *State.NextToken;
   const FormatToken &Previous = *Current.Previous;
   assert(&Previous == Current.Previous);
-  if (!Current.CanBreakBefore &&
-      !(State.Stack.back().BreakBeforeClosingBrace &&
-        Current.closesBlockOrBlockTypeList(Style)))
+  if (!Current.CanBreakBefore && !(State.Stack.back().BreakBeforeClosingBrace &&
+                                   Current.closesBlockOrBlockTypeList(Style)))
     return false;
   // The opening "{" of a braced list has to be on the same line as the first
   // element if it is nested in another braced init list or function call.
@@ -264,7 +323,8 @@ bool ContinuationIndenter::mustBreak(const LineState &State) {
     // We need special cases for ">>" which we have split into two ">" while
     // lexing in order to make template parsing easier.
     bool IsComparison = (Previous.getPrecedence() == prec::Relational ||
-                         Previous.getPrecedence() == prec::Equality) &&
+                         Previous.getPrecedence() == prec::Equality ||
+                         Previous.getPrecedence() == prec::Spaceship) &&
                         Previous.Previous &&
                         Previous.Previous->isNot(TT_BinaryOperator); // For >>.
     bool LHSIsBinaryExpr =
@@ -316,6 +376,12 @@ bool ContinuationIndenter::mustBreak(const LineState &State) {
                                      Previous.TokenText == "\'\\n\'"))))
     return true;
 
+  if (Previous.is(TT_BlockComment) && Previous.IsMultiline)
+    return true;
+
+  if (State.NoContinuation)
+    return true;
+
   return false;
 }
 
@@ -325,6 +391,8 @@ unsigned ContinuationIndenter::addTokenToState(LineState &State, bool Newline,
   const FormatToken &Current = *State.NextToken;
 
   assert(!State.Stack.empty());
+  State.NoContinuation = false;
+
   if ((Current.is(TT_ImplicitStringLiteral) &&
        (Current.Previous->Tok.getIdentifierInfo() == nullptr ||
         Current.Previous->Tok.getIdentifierInfo()->getPPKeywordID() ==
@@ -376,9 +444,25 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
 
   unsigned Spaces = Current.SpacesRequiredBefore + ExtraSpaces;
 
+  // Indent preprocessor directives after the hash if required.
+  int PPColumnCorrection = 0;
+  if (Style.IndentPPDirectives == FormatStyle::PPDIS_AfterHash &&
+      Previous.is(tok::hash) && State.FirstIndent > 0 &&
+      (State.Line->Type == LT_PreprocessorDirective ||
+       State.Line->Type == LT_ImportStatement)) {
+    Spaces += State.FirstIndent;
+
+    // For preprocessor indent with tabs, State.Column will be 1 because of the
+    // hash. This causes second-level indents onward to have an extra space
+    // after the tabs. We avoid this misalignment by subtracting 1 from the
+    // column value passed to replaceWhitespace().
+    if (Style.UseTab != FormatStyle::UT_Never)
+      PPColumnCorrection = -1;
+  }
+
   if (!DryRun)
     Whitespaces.replaceWhitespace(Current, /*Newlines=*/0, Spaces,
-                                  State.Column + Spaces);
+                                  State.Column + Spaces + PPColumnCorrection);
 
   // If "BreakBeforeInheritanceComma" mode, don't break within the inheritance
   // declaration unless there is multiple inheritance.
@@ -405,9 +489,8 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
   if (Style.AlignAfterOpenBracket == FormatStyle::BAS_AlwaysBreak &&
       Previous.isOneOf(tok::l_paren, TT_TemplateOpener, tok::l_square) &&
       State.Column > getNewLineColumn(State) &&
-      (!Previous.Previous ||
-       !Previous.Previous->isOneOf(tok::kw_for, tok::kw_while,
-                                   tok::kw_switch)) &&
+      (!Previous.Previous || !Previous.Previous->isOneOf(
+                                 tok::kw_for, tok::kw_while, tok::kw_switch)) &&
       // Don't do this for simple (no expressions) one-argument function calls
       // as that feels like needlessly wasting whitespace, e.g.:
       //
@@ -454,7 +537,8 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
        (P->is(TT_ConditionalExpr) && P->is(tok::colon))) &&
       !P->isOneOf(TT_OverloadedOperator, TT_CtorInitializerComma) &&
       P->getPrecedence() != prec::Assignment &&
-      P->getPrecedence() != prec::Relational) {
+      P->getPrecedence() != prec::Relational &&
+      P->getPrecedence() != prec::Spaceship) {
     bool BreakBeforeOperator =
         P->MustBreakBefore || P->is(tok::lessless) ||
         (P->is(TT_BinaryOperator) &&
@@ -619,8 +703,18 @@ unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
     State.Stack.back().BreakBeforeParameter = false;
 
   if (!DryRun) {
+    unsigned MaxEmptyLinesToKeep = Style.MaxEmptyLinesToKeep + 1;
+    if (Current.is(tok::r_brace) && Current.MatchingParen &&
+        // Only strip trailing empty lines for l_braces that have children, i.e.
+        // for function expressions (lambdas, arrows, etc).
+        !Current.MatchingParen->Children.empty()) {
+      // lambdas and arrow functions are expressions, thus their r_brace is not
+      // on its own line, and thus not covered by UnwrappedLineFormatter's logic
+      // about removing empty lines on closing blocks. Special case them here.
+      MaxEmptyLinesToKeep = 1;
+    }
     unsigned Newlines = std::max(
-        1u, std::min(Current.NewlinesBefore, Style.MaxEmptyLinesToKeep + 1));
+        1u, std::min(Current.NewlinesBefore, MaxEmptyLinesToKeep));
     bool ContinuePPDirective =
         State.Line->InPPDirective && State.Line->Type != LT_ImportStatement;
     Whitespaces.replaceWhitespace(Current, Newlines, State.Column, State.Column,
@@ -661,9 +755,7 @@ unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
   // before the corresponding } or ].
   if (PreviousNonComment &&
       (PreviousNonComment->isOneOf(tok::l_brace, TT_ArrayInitializerLSquare) ||
-       opensProtoMessageField(*PreviousNonComment, Style) ||
-       (PreviousNonComment->is(TT_TemplateString) &&
-        PreviousNonComment->opensScope())))
+       opensProtoMessageField(*PreviousNonComment, Style)))
     State.Stack.back().BreakBeforeClosingBrace = true;
 
   if (State.Stack.back().AvoidBinPacking) {
@@ -731,7 +823,10 @@ unsigned ContinuationIndenter::getNewLineColumn(const LineState &State) {
   if (NextNonComment->is(TT_TemplateString) && NextNonComment->closesScope())
     return State.Stack[State.Stack.size() - 2].LastSpace;
   if (Current.is(tok::identifier) && Current.Next &&
-      Current.Next->is(TT_DictLiteral))
+      (Current.Next->is(TT_DictLiteral) ||
+       ((Style.Language == FormatStyle::LK_Proto ||
+         Style.Language == FormatStyle::LK_TextProto) &&
+        Current.Next->isOneOf(TT_TemplateOpener, tok::l_brace))))
     return State.Stack.back().Indent;
   if (NextNonComment->is(TT_ObjCStringLiteral) &&
       State.StartOfStringLiteral != 0)
@@ -871,8 +966,10 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
     //       Next(...)
     //       ^ line up here.
     State.Stack.back().Indent =
-        State.Column + (Style.BreakConstructorInitializers ==
-                            FormatStyle::BCIS_BeforeComma ? 0 : 2);
+        State.Column +
+        (Style.BreakConstructorInitializers == FormatStyle::BCIS_BeforeComma
+             ? 0
+             : 2);
     State.Stack.back().NestedBlockIndent = State.Stack.back().Indent;
     if (Style.ConstructorInitializerAllOnOneLineOrOnePerLine)
       State.Stack.back().AvoidBinPacking = true;
@@ -884,7 +981,7 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
         State.FirstIndent + Style.ConstructorInitializerIndentWidth;
     State.Stack.back().NestedBlockIndent = State.Stack.back().Indent;
     if (Style.ConstructorInitializerAllOnOneLineOrOnePerLine)
-        State.Stack.back().AvoidBinPacking = true;
+      State.Stack.back().AvoidBinPacking = true;
   }
   if (Current.is(TT_InheritanceColon))
     State.Stack.back().Indent =
@@ -912,8 +1009,9 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
         State.Stack[i].NoLineBreak = true;
     State.Stack[State.Stack.size() - 2].NestedBlockInlined = false;
   }
-  if (Previous && (Previous->isOneOf(tok::l_paren, tok::comma, tok::colon) ||
-                   Previous->isOneOf(TT_BinaryOperator, TT_ConditionalExpr)) &&
+  if (Previous &&
+      (Previous->isOneOf(tok::l_paren, tok::comma, tok::colon) ||
+       Previous->isOneOf(TT_BinaryOperator, TT_ConditionalExpr)) &&
       !Previous->isOneOf(TT_DictLiteral, TT_ObjCMethodExpr)) {
     State.Stack.back().NestedBlockInlined =
         !Newline &&
@@ -922,13 +1020,8 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
 
   moveStatePastFakeLParens(State, Newline);
   moveStatePastScopeCloser(State);
-  if (Current.is(TT_TemplateString) && Current.opensScope())
-    State.Stack.back().LastSpace =
-        (Current.IsMultiline ? Current.LastLineColumnWidth
-                             : State.Column + Current.ColumnWidth) -
-        strlen("${");
-  bool CanBreakProtrudingToken = !State.Stack.back().NoLineBreak &&
-                                 !State.Stack.back().NoLineBreakInOperand;
+  bool AllowBreak = !State.Stack.back().NoLineBreak &&
+                    !State.Stack.back().NoLineBreakInOperand;
   moveStatePastScopeOpener(State, Newline);
   moveStatePastFakeRParens(State);
 
@@ -942,13 +1035,9 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
 
   State.Column += Current.ColumnWidth;
   State.NextToken = State.NextToken->Next;
-  unsigned Penalty = 0;
-  if (CanBreakProtrudingToken)
-    Penalty = breakProtrudingToken(Current, State, DryRun);
-  if (State.Column > getColumnLimit(State)) {
-    unsigned ExcessCharacters = State.Column - getColumnLimit(State);
-    Penalty += Style.PenaltyExcessCharacter * ExcessCharacters;
-  }
+
+  unsigned Penalty =
+      handleEndOfLine(Current, State, DryRun, AllowBreak);
 
   if (Current.Role)
     Current.Role->formatFromToken(State, this, DryRun);
@@ -1072,14 +1161,13 @@ void ContinuationIndenter::moveStatePastScopeOpener(LineState &State,
     bool EndsInComma = Current.MatchingParen &&
                        Current.MatchingParen->Previous &&
                        Current.MatchingParen->Previous->is(tok::comma);
-    AvoidBinPacking =
-        EndsInComma || Current.is(TT_DictLiteral) ||
-        Style.Language == FormatStyle::LK_Proto ||
-        Style.Language == FormatStyle::LK_TextProto ||
-        !Style.BinPackArguments ||
-        (NextNoComment &&
-         NextNoComment->isOneOf(TT_DesignatedInitializerPeriod,
-                                TT_DesignatedInitializerLSquare));
+    AvoidBinPacking = EndsInComma || Current.is(TT_DictLiteral) ||
+                      Style.Language == FormatStyle::LK_Proto ||
+                      Style.Language == FormatStyle::LK_TextProto ||
+                      !Style.BinPackArguments ||
+                      (NextNoComment &&
+                       NextNoComment->isOneOf(TT_DesignatedInitializerPeriod,
+                                              TT_DesignatedInitializerLSquare));
     BreakBeforeParameter = EndsInComma;
     if (Current.ParameterCount > 1)
       NestedBlockIndent = std::max(NestedBlockIndent, State.Column + 1);
@@ -1098,18 +1186,6 @@ void ContinuationIndenter::moveStatePastScopeOpener(LineState &State,
       LastSpace = std::max(LastSpace, State.Stack.back().Indent);
     }
 
-    // JavaScript template strings are special as we always want to indent
-    // nested expressions relative to the ${}. Otherwise, this can create quite
-    // a mess.
-    if (Current.is(TT_TemplateString)) {
-      unsigned Column = Current.IsMultiline
-                            ? Current.LastLineColumnWidth
-                            : State.Column + Current.ColumnWidth;
-      NewIndent = Column;
-      LastSpace = Column;
-      NestedBlockIndent = Column;
-    }
-
     bool EndsInComma =
         Current.MatchingParen &&
         Current.MatchingParen->getPreviousNonComment() &&
@@ -1200,11 +1276,93 @@ void ContinuationIndenter::moveStateToNewBlock(LineState &State) {
   State.Stack.back().BreakBeforeParameter = true;
 }
 
-unsigned ContinuationIndenter::addMultilineToken(const FormatToken &Current,
-                                                 LineState &State) {
-  if (!Current.IsMultiline)
+static unsigned getLastLineEndColumn(StringRef Text, unsigned StartColumn,
+                                     unsigned TabWidth,
+                                     encoding::Encoding Encoding) {
+  size_t LastNewlinePos = Text.find_last_of("\n");
+  if (LastNewlinePos == StringRef::npos) {
+    return StartColumn +
+           encoding::columnWidthWithTabs(Text, StartColumn, TabWidth, Encoding);
+  } else {
+    return encoding::columnWidthWithTabs(Text.substr(LastNewlinePos),
+                                         /*StartColumn=*/0, TabWidth, Encoding);
+  }
+}
+
+unsigned ContinuationIndenter::reformatRawStringLiteral(
+    const FormatToken &Current, LineState &State,
+    const FormatStyle &RawStringStyle, bool DryRun) {
+  unsigned StartColumn = State.Column - Current.ColumnWidth;
+  auto Delimiter = *getRawStringDelimiter(Current.TokenText);
+  // The text of a raw string is between the leading 'R"delimiter(' and the
+  // trailing 'delimiter)"'.
+  unsigned PrefixSize = 3 + Delimiter.size();
+  unsigned SuffixSize = 2 + Delimiter.size();
+
+  // The first start column is the column the raw text starts.
+  unsigned FirstStartColumn = StartColumn + PrefixSize;
+
+  // The next start column is the intended indentation a line break inside
+  // the raw string at level 0. It is determined by the following rules:
+  //   - if the content starts on newline, it is one level more than the current
+  //     indent, and
+  //   - if the content does not start on a newline, it is the first start
+  //     column.
+  // These rules have the advantage that the formatted content both does not
+  // violate the rectangle rule and visually flows within the surrounding
+  // source.
+  bool ContentStartsOnNewline = Current.TokenText[PrefixSize] == '\n';
+  unsigned NextStartColumn = ContentStartsOnNewline
+                                 ? State.Stack.back().Indent + Style.IndentWidth
+                                 : FirstStartColumn;
+
+  // The last start column is the column the raw string suffix starts if it is
+  // put on a newline.
+  // The last start column is the intended indentation of the raw string postfix
+  // if it is put on a newline. It is determined by the following rules:
+  //   - if the raw string prefix starts on a newline, it is the column where
+  //     that raw string prefix starts, and
+  //   - if the raw string prefix does not start on a newline, it is the current
+  //     indent.
+  unsigned LastStartColumn = Current.NewlinesBefore
+                                 ? FirstStartColumn - PrefixSize
+                                 : State.Stack.back().Indent;
+
+  std::string RawText =
+      Current.TokenText.substr(PrefixSize).drop_back(SuffixSize);
+
+  std::pair<tooling::Replacements, unsigned> Fixes = internal::reformat(
+      RawStringStyle, RawText, {tooling::Range(0, RawText.size())},
+      FirstStartColumn, NextStartColumn, LastStartColumn, "<stdin>",
+      /*Status=*/nullptr);
+
+  auto NewCode = applyAllReplacements(RawText, Fixes.first);
+  tooling::Replacements NoFixes;
+  if (!NewCode) {
+    State.Column += Current.ColumnWidth;
     return 0;
+  }
+  if (!DryRun) {
+    SourceLocation OriginLoc =
+        Current.Tok.getLocation().getLocWithOffset(PrefixSize);
+    for (const tooling::Replacement &Fix : Fixes.first) {
+      auto Err = Whitespaces.addReplacement(tooling::Replacement(
+          SourceMgr, OriginLoc.getLocWithOffset(Fix.getOffset()),
+          Fix.getLength(), Fix.getReplacementText()));
+      if (Err) {
+        llvm::errs() << "Failed to reformat raw string: "
+                     << llvm::toString(std::move(Err)) << "\n";
+      }
+    }
+  }
+  unsigned RawLastLineEndColumn = getLastLineEndColumn(
+      *NewCode, FirstStartColumn, Style.TabWidth, Encoding);
+  State.Column = RawLastLineEndColumn + SuffixSize;
+  return Fixes.second;
+}
 
+unsigned ContinuationIndenter::addMultilineToken(const FormatToken &Current,
+                                                 LineState &State) {
   // Break before further function parameters on all levels.
   for (unsigned i = 0, e = State.Stack.size(); i != e; ++i)
     State.Stack[i].BreakBeforeParameter = true;
@@ -1219,33 +1377,85 @@ unsigned ContinuationIndenter::addMultilineToken(const FormatToken &Current,
   return 0;
 }
 
-unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
-                                                    LineState &State,
-                                                    bool DryRun) {
-  // Don't break multi-line tokens other than block comments. Instead, just
-  // update the state.
-  if (Current.isNot(TT_BlockComment) && Current.IsMultiline)
-    return addMultilineToken(Current, State);
-
-  // Don't break implicit string literals or import statements.
-  if (Current.is(TT_ImplicitStringLiteral) ||
-      State.Line->Type == LT_ImportStatement)
-    return 0;
+unsigned ContinuationIndenter::handleEndOfLine(const FormatToken &Current,
+                                               LineState &State, bool DryRun,
+                                               bool AllowBreak) {
+  unsigned Penalty = 0;
+  // Compute the raw string style to use in case this is a raw string literal
+  // that can be reformatted.
+  auto RawStringStyle = getRawStringStyle(Current, State);
+  if (RawStringStyle) {
+    Penalty = reformatRawStringLiteral(Current, State, *RawStringStyle, DryRun);
+  } else if (Current.IsMultiline && Current.isNot(TT_BlockComment)) {
+    // Don't break multi-line tokens other than block comments and raw string
+    // literals. Instead, just update the state.
+    Penalty = addMultilineToken(Current, State);
+  } else if (State.Line->Type != LT_ImportStatement) {
+    // We generally don't break import statements.
+    LineState OriginalState = State;
+
+    // Whether we force the reflowing algorithm to stay strictly within the
+    // column limit.
+    bool Strict = false;
+    // Whether the first non-strict attempt at reflowing did intentionally
+    // exceed the column limit.
+    bool Exceeded = false;
+    std::tie(Penalty, Exceeded) = breakProtrudingToken(
+        Current, State, AllowBreak, /*DryRun=*/true, Strict);
+    if (Exceeded) {
+      // If non-strict reflowing exceeds the column limit, try whether strict
+      // reflowing leads to an overall lower penalty.
+      LineState StrictState = OriginalState;
+      unsigned StrictPenalty =
+          breakProtrudingToken(Current, StrictState, AllowBreak,
+                               /*DryRun=*/true, /*Strict=*/true)
+              .first;
+      Strict = StrictPenalty <= Penalty;
+      if (Strict) {
+        Penalty = StrictPenalty;
+        State = StrictState;
+      }
+    }
+    if (!DryRun) {
+      // If we're not in dry-run mode, apply the changes with the decision on
+      // strictness made above.
+      breakProtrudingToken(Current, OriginalState, AllowBreak, /*DryRun=*/false,
+                           Strict);
+    }
+  }
+  if (State.Column > getColumnLimit(State)) {
+    unsigned ExcessCharacters = State.Column - getColumnLimit(State);
+    Penalty += Style.PenaltyExcessCharacter * ExcessCharacters;
+  }
+  return Penalty;
+}
 
-  if (!Current.isStringLiteral() && !Current.is(tok::comment))
-    return 0;
+llvm::Optional<FormatStyle>
+ContinuationIndenter::getRawStringStyle(const FormatToken &Current,
+                                        const LineState &State) {
+  if (!Current.isStringLiteral())
+    return None;
+  auto Delimiter = getRawStringDelimiter(Current.TokenText);
+  if (!Delimiter)
+    return None;
+  auto RawStringStyle = RawStringFormats.get(*Delimiter);
+  if (!RawStringStyle)
+    return None;
+  RawStringStyle->ColumnLimit = getColumnLimit(State);
+  return RawStringStyle;
+}
 
-  std::unique_ptr<BreakableToken> Token;
+std::unique_ptr<BreakableToken> ContinuationIndenter::createBreakableToken(
+    const FormatToken &Current, LineState &State, bool AllowBreak) {
   unsigned StartColumn = State.Column - Current.ColumnWidth;
-  unsigned ColumnLimit = getColumnLimit(State);
-
   if (Current.isStringLiteral()) {
     // FIXME: String literal breaking is currently disabled for Java and JS, as
     // it requires strings to be merged using "+" which we don't support.
     if (Style.Language == FormatStyle::LK_Java ||
         Style.Language == FormatStyle::LK_JavaScript ||
-        !Style.BreakStringLiterals)
-      return 0;
+        !Style.BreakStringLiterals ||
+        !AllowBreak)
+      return nullptr;
 
     // Don't break string literals inside preprocessor directives (except for
     // #define directives, as their contents are stored in separate lines and
@@ -1253,11 +1463,11 @@ unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
     // This way we avoid breaking code with line directives and unknown
     // preprocessor directives that contain long string literals.
     if (State.Line->Type == LT_PreprocessorDirective)
-      return 0;
+      return nullptr;
     // Exempts unterminated string literals from line breaking. The user will
     // likely want to terminate the string before any line breaking is done.
     if (Current.IsUnterminatedLiteral)
-      return 0;
+      return nullptr;
 
     StringRef Text = Current.TokenText;
     StringRef Prefix;
@@ -1272,114 +1482,359 @@ unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
           Text.startswith(Prefix = "u8\"") ||
           Text.startswith(Prefix = "L\""))) ||
         (Text.startswith(Prefix = "_T(\"") && Text.endswith(Postfix = "\")"))) {
-      Token.reset(new BreakableStringLiteral(Current, StartColumn, Prefix,
-                                             Postfix, State.Line->InPPDirective,
-                                             Encoding, Style));
-    } else {
-      return 0;
+      return llvm::make_unique<BreakableStringLiteral>(
+          Current, StartColumn, Prefix, Postfix, State.Line->InPPDirective,
+          Encoding, Style);
     }
   } else if (Current.is(TT_BlockComment)) {
-    if (!Current.isTrailingComment() || !Style.ReflowComments ||
+    if (!Style.ReflowComments ||
         // If a comment token switches formatting, like
         // /* clang-format on */, we don't want to break it further,
         // but we may still want to adjust its indentation.
-        switchesFormatting(Current))
-      return addMultilineToken(Current, State);
-    Token.reset(new BreakableBlockComment(
+        switchesFormatting(Current)) {
+      return nullptr;
+    }
+    return llvm::make_unique<BreakableBlockComment>(
         Current, StartColumn, Current.OriginalColumn, !Current.Previous,
-        State.Line->InPPDirective, Encoding, Style));
+        State.Line->InPPDirective, Encoding, Style);
   } else if (Current.is(TT_LineComment) &&
              (Current.Previous == nullptr ||
               Current.Previous->isNot(TT_ImplicitStringLiteral))) {
     if (!Style.ReflowComments ||
         CommentPragmasRegex.match(Current.TokenText.substr(2)) ||
         switchesFormatting(Current))
-      return 0;
-    Token.reset(new BreakableLineCommentSection(
+      return nullptr;
+    return llvm::make_unique<BreakableLineCommentSection>(
         Current, StartColumn, Current.OriginalColumn, !Current.Previous,
-        /*InPPDirective=*/false, Encoding, Style));
+        /*InPPDirective=*/false, Encoding, Style);
+  }
+  return nullptr;
+}
+
+std::pair<unsigned, bool>
+ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
+                                           LineState &State, bool AllowBreak,
+                                           bool DryRun, bool Strict) {
+  std::unique_ptr<const BreakableToken> Token =
+      createBreakableToken(Current, State, AllowBreak);
+  if (!Token)
+    return {0, false};
+  assert(Token->getLineCount() > 0);
+  unsigned ColumnLimit = getColumnLimit(State);
+  if (Current.is(TT_LineComment)) {
     // We don't insert backslashes when breaking line comments.
     ColumnLimit = Style.ColumnLimit;
-  } else {
-    return 0;
   }
   if (Current.UnbreakableTailLength >= ColumnLimit)
-    return 0;
-
-  unsigned RemainingSpace = ColumnLimit - Current.UnbreakableTailLength;
-  bool BreakInserted = false;
+    return {0, false};
+  // ColumnWidth was already accounted into State.Column before calling
+  // breakProtrudingToken.
+  unsigned StartColumn = State.Column - Current.ColumnWidth;
+  unsigned NewBreakPenalty = Current.isStringLiteral()
+                                 ? Style.PenaltyBreakString
+                                 : Style.PenaltyBreakComment;
+  // Stores whether we intentionally decide to let a line exceed the column
+  // limit.
+  bool Exceeded = false;
+  // Stores whether we introduce a break anywhere in the token.
+  bool BreakInserted = Token->introducesBreakBeforeToken();
+  // Store whether we inserted a new line break at the end of the previous
+  // logical line.
+  bool NewBreakBefore = false;
   // We use a conservative reflowing strategy. Reflow starts after a line is
   // broken or the corresponding whitespace compressed. Reflow ends as soon as a
   // line that doesn't get reflown with the previous line is reached.
-  bool ReflowInProgress = false;
+  bool Reflow = false;
+  // Keep track of where we are in the token:
+  // Where we are in the content of the current logical line.
+  unsigned TailOffset = 0;
+  // The column number we're currently at.
+  unsigned ContentStartColumn =
+      Token->getContentStartColumn(0, /*Break=*/false);
+  // The number of columns left in the current logical line after TailOffset.
+  unsigned RemainingTokenColumns =
+      Token->getRemainingLength(0, TailOffset, ContentStartColumn);
+  // Adapt the start of the token, for example indent.
+  if (!DryRun)
+    Token->adaptStartOfLine(0, Whitespaces);
+
   unsigned Penalty = 0;
-  unsigned RemainingTokenColumns = 0;
+  DEBUG(llvm::dbgs() << "Breaking protruding token at column " << StartColumn
+                     << ".\n");
   for (unsigned LineIndex = 0, EndIndex = Token->getLineCount();
        LineIndex != EndIndex; ++LineIndex) {
-    BreakableToken::Split SplitBefore(StringRef::npos, 0);
-    if (ReflowInProgress) {
-      SplitBefore = Token->getSplitBefore(LineIndex, RemainingTokenColumns,
-                                          RemainingSpace, CommentPragmasRegex);
-    }
-    ReflowInProgress = SplitBefore.first != StringRef::npos;
-    unsigned TailOffset =
-        ReflowInProgress ? (SplitBefore.first + SplitBefore.second) : 0;
-    if (!DryRun)
-      Token->replaceWhitespaceBefore(LineIndex, RemainingTokenColumns,
-                                     RemainingSpace, SplitBefore, Whitespaces);
-    RemainingTokenColumns = Token->getLineLengthAfterSplitBefore(
-        LineIndex, TailOffset, RemainingTokenColumns, ColumnLimit, SplitBefore);
-    while (RemainingTokenColumns > RemainingSpace) {
-      BreakableToken::Split Split = Token->getSplit(
-          LineIndex, TailOffset, ColumnLimit, CommentPragmasRegex);
+    DEBUG(llvm::dbgs() << "  Line: " << LineIndex << " (Reflow: " << Reflow
+                       << ")\n");
+    NewBreakBefore = false;
+    // If we did reflow the previous line, we'll try reflowing again. Otherwise
+    // we'll start reflowing if the current line is broken or whitespace is
+    // compressed.
+    bool TryReflow = Reflow;
+    // Break the current token until we can fit the rest of the line.
+    while (ContentStartColumn + RemainingTokenColumns > ColumnLimit) {
+      DEBUG(llvm::dbgs() << "    Over limit, need: "
+                         << (ContentStartColumn + RemainingTokenColumns)
+                         << ", space: " << ColumnLimit
+                         << ", reflown prefix: " << ContentStartColumn
+                         << ", offset in line: " << TailOffset << "\n");
+      // If the current token doesn't fit, find the latest possible split in the
+      // current line so that breaking at it will be under the column limit.
+      // FIXME: Use the earliest possible split while reflowing to correctly
+      // compress whitespace within a line.
+      BreakableToken::Split Split =
+          Token->getSplit(LineIndex, TailOffset, ColumnLimit,
+                          ContentStartColumn, CommentPragmasRegex);
       if (Split.first == StringRef::npos) {
-        // The last line's penalty is handled in addNextStateToQueue().
+        // No break opportunity - update the penalty and continue with the next
+        // logical line.
         if (LineIndex < EndIndex - 1)
+          // The last line's penalty is handled in addNextStateToQueue().
           Penalty += Style.PenaltyExcessCharacter *
-                     (RemainingTokenColumns - RemainingSpace);
+                     (ContentStartColumn + RemainingTokenColumns - ColumnLimit);
+        DEBUG(llvm::dbgs() << "    No break opportunity.\n");
         break;
       }
       assert(Split.first != 0);
 
-      // Check if compressing the whitespace range will bring the line length
-      // under the limit. If that is the case, we perform whitespace compression
-      // instead of inserting a line break.
-      unsigned RemainingTokenColumnsAfterCompression =
-          Token->getLineLengthAfterCompression(RemainingTokenColumns, Split);
-      if (RemainingTokenColumnsAfterCompression <= RemainingSpace) {
-        RemainingTokenColumns = RemainingTokenColumnsAfterCompression;
-        ReflowInProgress = true;
-        if (!DryRun)
-          Token->compressWhitespace(LineIndex, TailOffset, Split, Whitespaces);
-        break;
+      if (Token->supportsReflow()) {
+        // Check whether the next natural split point after the current one can
+        // still fit the line, either because we can compress away whitespace,
+        // or because the penalty the excess characters introduce is lower than
+        // the break penalty.
+        // We only do this for tokens that support reflowing, and thus allow us
+        // to change the whitespace arbitrarily (e.g. comments).
+        // Other tokens, like string literals, can be broken on arbitrary
+        // positions.
+
+        // First, compute the columns from TailOffset to the next possible split
+        // position.
+        // For example:
+        // ColumnLimit:     |
+        // // Some text   that    breaks
+        //    ^ tail offset
+        //             ^-- split
+        //    ^-------- to split columns
+        //                    ^--- next split
+        //    ^--------------- to next split columns
+        unsigned ToSplitColumns = Token->getRangeLength(
+            LineIndex, TailOffset, Split.first, ContentStartColumn);
+        DEBUG(llvm::dbgs() << "    ToSplit: " << ToSplitColumns << "\n");
+
+        BreakableToken::Split NextSplit = Token->getSplit(
+            LineIndex, TailOffset + Split.first + Split.second, ColumnLimit,
+            ContentStartColumn + ToSplitColumns + 1, CommentPragmasRegex);
+        // Compute the columns necessary to fit the next non-breakable sequence
+        // into the current line.
+        unsigned ToNextSplitColumns = 0;
+        if (NextSplit.first == StringRef::npos) {
+          ToNextSplitColumns = Token->getRemainingLength(LineIndex, TailOffset,
+                                                         ContentStartColumn);
+        } else {
+          ToNextSplitColumns = Token->getRangeLength(
+              LineIndex, TailOffset,
+              Split.first + Split.second + NextSplit.first, ContentStartColumn);
+        }
+        // Compress the whitespace between the break and the start of the next
+        // unbreakable sequence.
+        ToNextSplitColumns =
+            Token->getLengthAfterCompression(ToNextSplitColumns, Split);
+        DEBUG(llvm::dbgs() << "    ContentStartColumn: " << ContentStartColumn
+                           << "\n");
+        DEBUG(llvm::dbgs() << "    ToNextSplit: " << ToNextSplitColumns << "\n");
+        // If the whitespace compression makes us fit, continue on the current
+        // line.
+        bool ContinueOnLine =
+            ContentStartColumn + ToNextSplitColumns <= ColumnLimit;
+        unsigned ExcessCharactersPenalty = 0;
+        if (!ContinueOnLine && !Strict) {
+          // Similarly, if the excess characters' penalty is lower than the
+          // penalty of introducing a new break, continue on the current line.
+          ExcessCharactersPenalty =
+              (ContentStartColumn + ToNextSplitColumns - ColumnLimit) *
+              Style.PenaltyExcessCharacter;
+          DEBUG(llvm::dbgs()
+                << "    Penalty excess: " << ExcessCharactersPenalty
+                << "\n            break : " << NewBreakPenalty << "\n");
+          if (ExcessCharactersPenalty < NewBreakPenalty) {
+            Exceeded = true;
+            ContinueOnLine = true;
+          }
+        }
+        if (ContinueOnLine) {
+          DEBUG(llvm::dbgs() << "    Continuing on line...\n");
+          // The current line fits after compressing the whitespace - reflow
+          // the next line into it if possible.
+          TryReflow = true;
+          if (!DryRun)
+            Token->compressWhitespace(LineIndex, TailOffset, Split,
+                                      Whitespaces);
+          // When we continue on the same line, leave one space between content.
+          ContentStartColumn += ToSplitColumns + 1;
+          Penalty += ExcessCharactersPenalty;
+          TailOffset += Split.first + Split.second;
+          RemainingTokenColumns = Token->getRemainingLength(
+              LineIndex, TailOffset, ContentStartColumn);
+          continue;
+        }
       }
-
-      unsigned NewRemainingTokenColumns = Token->getLineLengthAfterSplit(
-          LineIndex, TailOffset + Split.first + Split.second, StringRef::npos);
+      DEBUG(llvm::dbgs() << "    Breaking...\n");
+      ContentStartColumn =
+          Token->getContentStartColumn(LineIndex, /*Break=*/true);
+      unsigned NewRemainingTokenColumns = Token->getRemainingLength(
+          LineIndex, TailOffset + Split.first + Split.second,
+          ContentStartColumn);
 
       // When breaking before a tab character, it may be moved by a few columns,
       // but will still be expanded to the next tab stop, so we don't save any
       // columns.
-      if (NewRemainingTokenColumns == RemainingTokenColumns)
+      if (NewRemainingTokenColumns == RemainingTokenColumns) {
+        // FIXME: Do we need to adjust the penalty?
         break;
-
+      }
       assert(NewRemainingTokenColumns < RemainingTokenColumns);
+
+      DEBUG(llvm::dbgs() << "    Breaking at: " << TailOffset + Split.first
+                         << ", " << Split.second << "\n");
       if (!DryRun)
         Token->insertBreak(LineIndex, TailOffset, Split, Whitespaces);
-      Penalty += Current.SplitPenalty;
-      unsigned ColumnsUsed =
-          Token->getLineLengthAfterSplit(LineIndex, TailOffset, Split.first);
-      if (ColumnsUsed > ColumnLimit) {
-        Penalty += Style.PenaltyExcessCharacter * (ColumnsUsed - ColumnLimit);
-      }
+
+      Penalty += NewBreakPenalty;
       TailOffset += Split.first + Split.second;
       RemainingTokenColumns = NewRemainingTokenColumns;
-      ReflowInProgress = true;
       BreakInserted = true;
+      NewBreakBefore = true;
     }
+    // In case there's another line, prepare the state for the start of the next
+    // line.
+    if (LineIndex + 1 != EndIndex) {
+      unsigned NextLineIndex = LineIndex + 1;
+      if (NewBreakBefore)
+        // After breaking a line, try to reflow the next line into the current
+        // one once RemainingTokenColumns fits.
+        TryReflow = true;
+      if (TryReflow) {
+        // We decided that we want to try reflowing the next line into the
+        // current one.
+        // We will now adjust the state as if the reflow is successful (in
+        // preparation for the next line), and see whether that works. If we
+        // decide that we cannot reflow, we will later reset the state to the
+        // start of the next line.
+        Reflow = false;
+        // As we did not continue breaking the line, RemainingTokenColumns is
+        // known to fit after ContentStartColumn. Adapt ContentStartColumn to
+        // the position at which we want to format the next line if we do
+        // actually reflow.
+        // When we reflow, we need to add a space between the end of the current
+        // line and the next line's start column.
+        ContentStartColumn += RemainingTokenColumns + 1;
+        // Get the split that we need to reflow next logical line into the end
+        // of the current one; the split will include any leading whitespace of
+        // the next logical line.
+        BreakableToken::Split SplitBeforeNext =
+            Token->getReflowSplit(NextLineIndex, CommentPragmasRegex);
+        DEBUG(llvm::dbgs() << "    Size of reflown text: " << ContentStartColumn
+                           << "\n    Potential reflow split: ");
+        if (SplitBeforeNext.first != StringRef::npos) {
+          DEBUG(llvm::dbgs() << SplitBeforeNext.first << ", "
+                             << SplitBeforeNext.second << "\n");
+          TailOffset = SplitBeforeNext.first + SplitBeforeNext.second;
+          // If the rest of the next line fits into the current line below the
+          // column limit, we can safely reflow.
+          RemainingTokenColumns = Token->getRemainingLength(
+              NextLineIndex, TailOffset, ContentStartColumn);
+          Reflow = true;
+          if (ContentStartColumn + RemainingTokenColumns > ColumnLimit) {
+            DEBUG(llvm::dbgs() << "    Over limit after reflow, need: "
+                               << (ContentStartColumn + RemainingTokenColumns)
+                               << ", space: " << ColumnLimit
+                               << ", reflown prefix: " << ContentStartColumn
+                               << ", offset in line: " << TailOffset << "\n");
+            // If the whole next line does not fit, try to find a point in
+            // the next line at which we can break so that attaching the part
+            // of the next line to that break point onto the current line is
+            // below the column limit.
+            BreakableToken::Split Split =
+                Token->getSplit(NextLineIndex, TailOffset, ColumnLimit,
+                                ContentStartColumn, CommentPragmasRegex);
+            if (Split.first == StringRef::npos) {
+              DEBUG(llvm::dbgs() << "    Did not find later break\n");
+              Reflow = false;
+            } else {
+              // Check whether the first split point gets us below the column
+              // limit. Note that we will execute this split below as part of
+              // the normal token breaking and reflow logic within the line.
+              unsigned ToSplitColumns = Token->getRangeLength(
+                  NextLineIndex, TailOffset, Split.first, ContentStartColumn);
+              if (ContentStartColumn + ToSplitColumns > ColumnLimit) {
+                DEBUG(llvm::dbgs() << "    Next split protrudes, need: "
+                                   << (ContentStartColumn + ToSplitColumns)
+                                   << ", space: " << ColumnLimit);
+                unsigned ExcessCharactersPenalty =
+                    (ContentStartColumn + ToSplitColumns - ColumnLimit) *
+                    Style.PenaltyExcessCharacter;
+                if (NewBreakPenalty < ExcessCharactersPenalty) {
+                  Reflow = false;
+                }
+              }
+            }
+          }
+        } else {
+          DEBUG(llvm::dbgs() << "not found.\n");
+        }
+      }
+      if (!Reflow) {
+        // If we didn't reflow into the next line, the only space to consider is
+        // the next logical line. Reset our state to match the start of the next
+        // line.
+        TailOffset = 0;
+        ContentStartColumn =
+            Token->getContentStartColumn(NextLineIndex, /*Break=*/false);
+        RemainingTokenColumns = Token->getRemainingLength(
+            NextLineIndex, TailOffset, ContentStartColumn);
+        // Adapt the start of the token, for example indent.
+        if (!DryRun)
+          Token->adaptStartOfLine(NextLineIndex, Whitespaces);
+      } else {
+        // If we found a reflow split and have added a new break before the next
+        // line, we are going to remove the line break at the start of the next
+        // logical line. For example, here we'll add a new line break after
+        // 'text', and subsequently delete the line break between 'that' and
+        // 'reflows'.
+        //   // some text that
+        //   // reflows
+        // ->
+        //   // some text
+        //   // that reflows
+        // When adding the line break, we also added the penalty for it, so we
+        // need to subtract that penalty again when we remove the line break due
+        // to reflowing.
+        if (NewBreakBefore) {
+          assert(Penalty >= NewBreakPenalty);
+          Penalty -= NewBreakPenalty;
+        }
+        if (!DryRun)
+          Token->reflow(NextLineIndex, Whitespaces);
+      }
+    }
+  }
+
+  BreakableToken::Split SplitAfterLastLine =
+      Token->getSplitAfterLastLine(TailOffset);
+  if (SplitAfterLastLine.first != StringRef::npos) {
+    DEBUG(llvm::dbgs() << "Replacing whitespace after last line.\n");
+    if (!DryRun)
+      Token->replaceWhitespaceAfterLastLine(TailOffset, SplitAfterLastLine,
+                                            Whitespaces);
+    ContentStartColumn =
+        Token->getContentStartColumn(Token->getLineCount() - 1, /*Break=*/true);
+    RemainingTokenColumns = Token->getRemainingLength(
+        Token->getLineCount() - 1,
+        TailOffset + SplitAfterLastLine.first + SplitAfterLastLine.second,
+        ContentStartColumn);
   }
 
-  State.Column = RemainingTokenColumns;
+  State.Column = ContentStartColumn + RemainingTokenColumns -
+                 Current.UnbreakableTailLength;
 
   if (BreakInserted) {
     // If we break the token inside a parameter list, we need to break before
@@ -1390,15 +1845,15 @@ unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
         State.Stack[i].BreakBeforeParameter = true;
     }
 
-    Penalty += Current.isStringLiteral() ? Style.PenaltyBreakString
-                                         : Style.PenaltyBreakComment;
+    if (Current.is(TT_BlockComment))
+      State.NoContinuation = true;
 
     State.Stack.back().LastSpace = StartColumn;
   }
 
   Token->updateNextToken(State);
 
-  return Penalty;
+  return {Penalty, Exceeded};
 }
 
 unsigned ContinuationIndenter::getColumnLimit(const LineState &State) const {
diff --git a/lib/Format/ContinuationIndenter.h b/lib/Format/ContinuationIndenter.h
index 9a06aa6f6267..ded7bfab4267 100644
--- a/lib/Format/ContinuationIndenter.h
+++ b/lib/Format/ContinuationIndenter.h
@@ -20,6 +20,8 @@
 #include "FormatToken.h"
 #include "clang/Format/Format.h"
 #include "llvm/Support/Regex.h"
+#include <map>
+#include <tuple>
 
 namespace clang {
 class SourceManager;
@@ -27,11 +29,21 @@ class SourceManager;
 namespace format {
 
 class AnnotatedLine;
+class BreakableToken;
 struct FormatToken;
 struct LineState;
 struct ParenState;
+struct RawStringFormatStyleManager;
 class WhitespaceManager;
 
+struct RawStringFormatStyleManager {
+  llvm::StringMap<FormatStyle> DelimiterStyle;
+
+  RawStringFormatStyleManager(const FormatStyle &CodeStyle);
+
+  llvm::Optional<FormatStyle> get(StringRef Delimiter) const;
+};
+
 class ContinuationIndenter {
 public:
   /// \brief Constructs a \c ContinuationIndenter to format \p Line starting in
@@ -44,9 +56,11 @@ public:
                        bool BinPackInconclusiveFunctions);
 
   /// \brief Get the initial state, i.e. the state after placing \p Line's
-  /// first token at \p FirstIndent.
-  LineState getInitialState(unsigned FirstIndent, const AnnotatedLine *Line,
-                            bool DryRun);
+  /// first token at \p FirstIndent. When reformatting a fragment of code, as in
+  /// the case of formatting inside raw string literals, \p FirstStartColumn is
+  /// the column at which the state of the parent formatter is.
+  LineState getInitialState(unsigned FirstIndent, unsigned FirstStartColumn,
+                            const AnnotatedLine *Line, bool DryRun);
 
   // FIXME: canBreak and mustBreak aren't strictly indentation-related. Find a
   // better home.
@@ -88,17 +102,52 @@ private:
   /// \brief Update 'State' with the next token opening a nested block.
   void moveStateToNewBlock(LineState &State);
 
+  /// \brief Reformats a raw string literal.
+  /// 
+  /// \returns An extra penalty induced by reformatting the token.
+  unsigned reformatRawStringLiteral(const FormatToken &Current,
+                                    LineState &State,
+                                    const FormatStyle &RawStringStyle,
+                                    bool DryRun);
+
+  /// \brief If the current token is at the end of the current line, handle
+  /// the transition to the next line.
+  unsigned handleEndOfLine(const FormatToken &Current, LineState &State,
+                           bool DryRun, bool AllowBreak);
+
+  /// \brief If \p Current is a raw string that is configured to be reformatted,
+  /// return the style to be used.
+  llvm::Optional<FormatStyle> getRawStringStyle(const FormatToken &Current,
+                                                const LineState &State);
+
   /// \brief If the current token sticks out over the end of the line, break
   /// it if possible.
   ///
-  /// \returns An extra penalty if a token was broken, otherwise 0.
+  /// \returns A pair (penalty, exceeded), where penalty is the extra penalty
+  /// when tokens are broken or lines exceed the column limit, and exceeded
+  /// indicates whether the algorithm purposefully left lines exceeding the
+  /// column limit.
   ///
-  /// The returned penalty will cover the cost of the additional line breaks and
-  /// column limit violation in all lines except for the last one. The penalty
-  /// for the column limit violation in the last line (and in single line
-  /// tokens) is handled in \c addNextStateToQueue.
-  unsigned breakProtrudingToken(const FormatToken &Current, LineState &State,
-                                bool DryRun);
+  /// The returned penalty will cover the cost of the additional line breaks
+  /// and column limit violation in all lines except for the last one. The
+  /// penalty for the column limit violation in the last line (and in single
+  /// line tokens) is handled in \c addNextStateToQueue.
+  ///
+  /// \p Strict indicates whether reflowing is allowed to leave characters
+  /// protruding the column limit; if true, lines will be split strictly within
+  /// the column limit where possible; if false, words are allowed to protrude
+  /// over the column limit as long as the penalty is less than the penalty
+  /// of a break.
+  std::pair<unsigned, bool> breakProtrudingToken(const FormatToken &Current,
+                                                 LineState &State,
+                                                 bool AllowBreak, bool DryRun,
+                                                 bool Strict);
+
+  /// \brief Returns the \c BreakableToken starting at \p Current, or nullptr
+  /// if the current token cannot be broken.
+  std::unique_ptr<BreakableToken>
+  createBreakableToken(const FormatToken &Current, LineState &State,
+                       bool AllowBreak);
 
   /// \brief Appends the next token to \p State and updates information
   /// necessary for indentation.
@@ -143,6 +192,7 @@ private:
   encoding::Encoding Encoding;
   bool BinPackInconclusiveFunctions;
   llvm::Regex CommentPragmasRegex;
+  const RawStringFormatStyleManager RawStringFormats;
 };
 
 struct ParenState {
@@ -318,6 +368,9 @@ struct LineState {
   /// \brief \c true if this line contains a continued for-loop section.
   bool LineContainsContinuedForLoopSection;
 
+  /// \brief \c true if \p NextToken should not continue this line.
+  bool NoContinuation;
+
   /// \brief The \c NestingLevel at the start of this line.
   unsigned StartOfLineLevel;
 
@@ -364,6 +417,8 @@ struct LineState {
     if (LineContainsContinuedForLoopSection !=
         Other.LineContainsContinuedForLoopSection)
       return LineContainsContinuedForLoopSection;
+    if (NoContinuation != Other.NoContinuation)
+      return NoContinuation;
     if (StartOfLineLevel != Other.StartOfLineLevel)
       return StartOfLineLevel < Other.StartOfLineLevel;
     if (LowestLevelOnLine != Other.LowestLevelOnLine)
diff --git a/lib/Format/Format.cpp b/lib/Format/Format.cpp
index 6fe5be2c815d..217c6729ee39 100644
--- a/lib/Format/Format.cpp
+++ b/lib/Format/Format.cpp
@@ -16,6 +16,7 @@
 #include "clang/Format/Format.h"
 #include "AffectedRangeManager.h"
 #include "ContinuationIndenter.h"
+#include "FormatInternal.h"
 #include "FormatTokenLexer.h"
 #include "NamespaceEndCommentsFixer.h"
 #include "SortJavaScriptImports.h"
@@ -45,6 +46,7 @@
 using clang::format::FormatStyle;
 
 LLVM_YAML_IS_SEQUENCE_VECTOR(clang::format::FormatStyle::IncludeCategory)
+LLVM_YAML_IS_SEQUENCE_VECTOR(clang::format::FormatStyle::RawStringFormat)
 
 namespace llvm {
 namespace yaml {
@@ -125,8 +127,10 @@ template <> struct ScalarEnumerationTraits<FormatStyle::BraceBreakingStyle> {
   }
 };
 
-template <> struct ScalarEnumerationTraits<FormatStyle::BreakConstructorInitializersStyle> {
-  static void enumeration(IO &IO, FormatStyle::BreakConstructorInitializersStyle &Value) {
+template <>
+struct ScalarEnumerationTraits<FormatStyle::BreakConstructorInitializersStyle> {
+  static void
+  enumeration(IO &IO, FormatStyle::BreakConstructorInitializersStyle &Value) {
     IO.enumCase(Value, "BeforeColon", FormatStyle::BCIS_BeforeColon);
     IO.enumCase(Value, "BeforeComma", FormatStyle::BCIS_BeforeComma);
     IO.enumCase(Value, "AfterColon", FormatStyle::BCIS_AfterColon);
@@ -134,6 +138,14 @@ template <> struct ScalarEnumerationTraits<FormatStyle::BreakConstructorInitiali
 };
 
 template <>
+struct ScalarEnumerationTraits<FormatStyle::PPDirectiveIndentStyle> {
+  static void enumeration(IO &IO, FormatStyle::PPDirectiveIndentStyle &Value) {
+    IO.enumCase(Value, "None", FormatStyle::PPDIS_None);
+    IO.enumCase(Value, "AfterHash", FormatStyle::PPDIS_AfterHash);
+  }
+};
+
+template <>
 struct ScalarEnumerationTraits<FormatStyle::ReturnTypeBreakingStyle> {
   static void enumeration(IO &IO, FormatStyle::ReturnTypeBreakingStyle &Value) {
     IO.enumCase(Value, "None", FormatStyle::RTBS_None);
@@ -181,8 +193,10 @@ template <> struct ScalarEnumerationTraits<FormatStyle::BracketAlignmentStyle> {
   }
 };
 
-template <> struct ScalarEnumerationTraits<FormatStyle::EscapedNewlineAlignmentStyle> {
-  static void enumeration(IO &IO, FormatStyle::EscapedNewlineAlignmentStyle &Value) {
+template <>
+struct ScalarEnumerationTraits<FormatStyle::EscapedNewlineAlignmentStyle> {
+  static void enumeration(IO &IO,
+                          FormatStyle::EscapedNewlineAlignmentStyle &Value) {
     IO.enumCase(Value, "DontAlign", FormatStyle::ENAS_DontAlign);
     IO.enumCase(Value, "Left", FormatStyle::ENAS_Left);
     IO.enumCase(Value, "Right", FormatStyle::ENAS_Right);
@@ -347,9 +361,11 @@ template <> struct MappingTraits<FormatStyle> {
                    Style.ExperimentalAutoDetectBinPacking);
     IO.mapOptional("FixNamespaceComments", Style.FixNamespaceComments);
     IO.mapOptional("ForEachMacros", Style.ForEachMacros);
+    IO.mapOptional("IncludeBlocks", Style.IncludeBlocks);
     IO.mapOptional("IncludeCategories", Style.IncludeCategories);
     IO.mapOptional("IncludeIsMainRegex", Style.IncludeIsMainRegex);
     IO.mapOptional("IndentCaseLabels", Style.IndentCaseLabels);
+    IO.mapOptional("IndentPPDirectives", Style.IndentPPDirectives);
     IO.mapOptional("IndentWidth", Style.IndentWidth);
     IO.mapOptional("IndentWrappedFunctionNames",
                    Style.IndentWrappedFunctionNames);
@@ -365,8 +381,7 @@ template <> struct MappingTraits<FormatStyle> {
     IO.mapOptional("ObjCSpaceAfterProperty", Style.ObjCSpaceAfterProperty);
     IO.mapOptional("ObjCSpaceBeforeProtocolList",
                    Style.ObjCSpaceBeforeProtocolList);
-    IO.mapOptional("PenaltyBreakAssignment",
-                   Style.PenaltyBreakAssignment);
+    IO.mapOptional("PenaltyBreakAssignment", Style.PenaltyBreakAssignment);
     IO.mapOptional("PenaltyBreakBeforeFirstCallParameter",
                    Style.PenaltyBreakBeforeFirstCallParameter);
     IO.mapOptional("PenaltyBreakComment", Style.PenaltyBreakComment);
@@ -377,11 +392,13 @@ template <> struct MappingTraits<FormatStyle> {
     IO.mapOptional("PenaltyReturnTypeOnItsOwnLine",
                    Style.PenaltyReturnTypeOnItsOwnLine);
     IO.mapOptional("PointerAlignment", Style.PointerAlignment);
+    IO.mapOptional("RawStringFormats", Style.RawStringFormats);
     IO.mapOptional("ReflowComments", Style.ReflowComments);
     IO.mapOptional("SortIncludes", Style.SortIncludes);
     IO.mapOptional("SortUsingDeclarations", Style.SortUsingDeclarations);
     IO.mapOptional("SpaceAfterCStyleCast", Style.SpaceAfterCStyleCast);
-    IO.mapOptional("SpaceAfterTemplateKeyword", Style.SpaceAfterTemplateKeyword);
+    IO.mapOptional("SpaceAfterTemplateKeyword",
+                   Style.SpaceAfterTemplateKeyword);
     IO.mapOptional("SpaceBeforeAssignmentOperators",
                    Style.SpaceBeforeAssignmentOperators);
     IO.mapOptional("SpaceBeforeParens", Style.SpaceBeforeParens);
@@ -411,6 +428,7 @@ template <> struct MappingTraits<FormatStyle::BraceWrappingFlags> {
     IO.mapOptional("AfterObjCDeclaration", Wrapping.AfterObjCDeclaration);
     IO.mapOptional("AfterStruct", Wrapping.AfterStruct);
     IO.mapOptional("AfterUnion", Wrapping.AfterUnion);
+    IO.mapOptional("AfterExternBlock", Wrapping.AfterExternBlock);
     IO.mapOptional("BeforeCatch", Wrapping.BeforeCatch);
     IO.mapOptional("BeforeElse", Wrapping.BeforeElse);
     IO.mapOptional("IndentBraces", Wrapping.IndentBraces);
@@ -427,6 +445,22 @@ template <> struct MappingTraits<FormatStyle::IncludeCategory> {
   }
 };
 
+template <> struct ScalarEnumerationTraits<FormatStyle::IncludeBlocksStyle> {
+  static void enumeration(IO &IO, FormatStyle::IncludeBlocksStyle &Value) {
+    IO.enumCase(Value, "Preserve", FormatStyle::IBS_Preserve);
+    IO.enumCase(Value, "Merge", FormatStyle::IBS_Merge);
+    IO.enumCase(Value, "Regroup", FormatStyle::IBS_Regroup);
+  }
+};
+
+template <> struct MappingTraits<FormatStyle::RawStringFormat> {
+  static void mapping(IO &IO, FormatStyle::RawStringFormat &Format) {
+    IO.mapOptional("Delimiter", Format.Delimiter);
+    IO.mapOptional("Language", Format.Language);
+    IO.mapOptional("BasedOnStyle", Format.BasedOnStyle);
+  }
+};
+
 // Allows to read vector<FormatStyle> while keeping default values.
 // IO.getContext() should contain a pointer to the FormatStyle structure, that
 // will be used to get default values for missing keys.
@@ -441,7 +475,7 @@ template <> struct DocumentListTraits<std::vector<FormatStyle>> {
     if (Index >= Seq.size()) {
       assert(Index == Seq.size());
       FormatStyle Template;
-      if (Seq.size() > 0 && Seq[0].Language == FormatStyle::LK_None) {
+      if (!Seq.empty() && Seq[0].Language == FormatStyle::LK_None) {
         Template = Seq[0];
       } else {
         Template = *((const FormatStyle *)IO.getContext());
@@ -491,9 +525,9 @@ static FormatStyle expandPresets(const FormatStyle &Style) {
   if (Style.BreakBeforeBraces == FormatStyle::BS_Custom)
     return Style;
   FormatStyle Expanded = Style;
-  Expanded.BraceWrapping = {false, false, false, false, false, false,
-                            false, false, false, false, false, true,
-                            true,  true};
+  Expanded.BraceWrapping = {false, false, false, false, false,
+                            false, false, false, false, false,
+                            false, false, true,  true,  true};
   switch (Style.BreakBeforeBraces) {
   case FormatStyle::BS_Linux:
     Expanded.BraceWrapping.AfterClass = true;
@@ -506,6 +540,7 @@ static FormatStyle expandPresets(const FormatStyle &Style) {
     Expanded.BraceWrapping.AfterFunction = true;
     Expanded.BraceWrapping.AfterStruct = true;
     Expanded.BraceWrapping.AfterUnion = true;
+    Expanded.BraceWrapping.AfterExternBlock = true;
     Expanded.BraceWrapping.SplitEmptyFunction = true;
     Expanded.BraceWrapping.SplitEmptyRecord = false;
     break;
@@ -522,13 +557,13 @@ static FormatStyle expandPresets(const FormatStyle &Style) {
     Expanded.BraceWrapping.AfterNamespace = true;
     Expanded.BraceWrapping.AfterObjCDeclaration = true;
     Expanded.BraceWrapping.AfterStruct = true;
+    Expanded.BraceWrapping.AfterExternBlock = true;
     Expanded.BraceWrapping.BeforeCatch = true;
     Expanded.BraceWrapping.BeforeElse = true;
     break;
   case FormatStyle::BS_GNU:
-    Expanded.BraceWrapping = {true, true, true, true, true, true,
-                              true, true, true, true, true, true,
-                              true, true};
+    Expanded.BraceWrapping = {true, true, true, true, true, true, true, true,
+                              true, true, true, true, true, true, true};
     break;
   case FormatStyle::BS_WebKit:
     Expanded.BraceWrapping.AfterFunction = true;
@@ -564,9 +599,9 @@ FormatStyle getLLVMStyle() {
   LLVMStyle.BreakBeforeBinaryOperators = FormatStyle::BOS_None;
   LLVMStyle.BreakBeforeTernaryOperators = true;
   LLVMStyle.BreakBeforeBraces = FormatStyle::BS_Attach;
-  LLVMStyle.BraceWrapping = {false, false, false, false, false, false,
-                             false, false, false, false, false, true,
-                             true,  true};
+  LLVMStyle.BraceWrapping = {false, false, false, false, false,
+                             false, false, false, false, false,
+                             false, false, true,  true,  true};
   LLVMStyle.BreakAfterJavaFieldAnnotations = false;
   LLVMStyle.BreakConstructorInitializers = FormatStyle::BCIS_BeforeColon;
   LLVMStyle.BreakBeforeInheritanceComma = false;
@@ -588,7 +623,9 @@ FormatStyle getLLVMStyle() {
                                  {"^(<|\"(gtest|gmock|isl|json)/)", 3},
                                  {".*", 1}};
   LLVMStyle.IncludeIsMainRegex = "(Test)?$";
+  LLVMStyle.IncludeBlocks = FormatStyle::IBS_Preserve;
   LLVMStyle.IndentCaseLabels = false;
+  LLVMStyle.IndentPPDirectives = FormatStyle::PPDIS_None;
   LLVMStyle.IndentWrappedFunctionNames = false;
   LLVMStyle.IndentWidth = 2;
   LLVMStyle.JavaScriptQuotes = FormatStyle::JSQS_Leave;
@@ -604,6 +641,7 @@ FormatStyle getLLVMStyle() {
   LLVMStyle.SpacesBeforeTrailingComments = 1;
   LLVMStyle.Standard = FormatStyle::LS_Cpp11;
   LLVMStyle.UseTab = FormatStyle::UT_Never;
+  LLVMStyle.RawStringFormats = {{"pb", FormatStyle::LK_TextProto, "google"}};
   LLVMStyle.ReflowComments = true;
   LLVMStyle.SpacesInParentheses = false;
   LLVMStyle.SpacesInSquareBrackets = false;
@@ -649,7 +687,8 @@ FormatStyle getGoogleStyle(FormatStyle::LanguageKind Language) {
   GoogleStyle.AlwaysBreakTemplateDeclarations = true;
   GoogleStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = true;
   GoogleStyle.DerivePointerAlignment = true;
-  GoogleStyle.IncludeCategories = {{"^<.*\\.h>", 1}, {"^<.*", 2}, {".*", 3}};
+  GoogleStyle.IncludeCategories = {
+      {"^<ext/.*\\.h>", 2}, {"^<.*\\.h>", 1}, {"^<.*", 2}, {".*", 3}};
   GoogleStyle.IncludeIsMainRegex = "([-_](test|unittest))?$";
   GoogleStyle.IndentCaseLabels = true;
   GoogleStyle.KeepEmptyLinesAtTheStartOfBlocks = false;
@@ -725,8 +764,7 @@ FormatStyle getMozillaStyle() {
   FormatStyle MozillaStyle = getLLVMStyle();
   MozillaStyle.AllowAllParametersOfDeclarationOnNextLine = false;
   MozillaStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Inline;
-  MozillaStyle.AlwaysBreakAfterReturnType =
-      FormatStyle::RTBS_TopLevel;
+  MozillaStyle.AlwaysBreakAfterReturnType = FormatStyle::RTBS_TopLevel;
   MozillaStyle.AlwaysBreakAfterDefinitionReturnType =
       FormatStyle::DRTBS_TopLevel;
   MozillaStyle.AlwaysBreakTemplateDeclarations = true;
@@ -879,7 +917,7 @@ public:
   JavaScriptRequoter(const Environment &Env, const FormatStyle &Style)
       : TokenAnalyzer(Env, Style) {}
 
-  tooling::Replacements
+  std::pair<tooling::Replacements, unsigned>
   analyze(TokenAnnotator &Annotator,
           SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
           FormatTokenLexer &Tokens) override {
@@ -887,7 +925,7 @@ public:
                                           AnnotatedLines.end());
     tooling::Replacements Result;
     requoteJSStringLiteral(AnnotatedLines, Result);
-    return Result;
+    return {Result, 0};
   }
 
 private:
@@ -968,7 +1006,7 @@ public:
             FormattingAttemptStatus *Status)
       : TokenAnalyzer(Env, Style), Status(Status) {}
 
-  tooling::Replacements
+  std::pair<tooling::Replacements, unsigned>
   analyze(TokenAnnotator &Annotator,
           SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
           FormatTokenLexer &Tokens) override {
@@ -987,17 +1025,23 @@ public:
     ContinuationIndenter Indenter(Style, Tokens.getKeywords(),
                                   Env.getSourceManager(), Whitespaces, Encoding,
                                   BinPackInconclusiveFunctions);
-    UnwrappedLineFormatter(&Indenter, &Whitespaces, Style, Tokens.getKeywords(),
-                           Env.getSourceManager(), Status)
-        .format(AnnotatedLines);
+    unsigned Penalty =
+        UnwrappedLineFormatter(&Indenter, &Whitespaces, Style,
+                               Tokens.getKeywords(), Env.getSourceManager(),
+                               Status)
+            .format(AnnotatedLines, /*DryRun=*/false,
+                    /*AdditionalIndent=*/0,
+                    /*FixBadIndentation=*/false,
+                    /*FirstStartColumn=*/Env.getFirstStartColumn(),
+                    /*NextStartColumn=*/Env.getNextStartColumn(),
+                    /*LastStartColumn=*/Env.getLastStartColumn());
     for (const auto &R : Whitespaces.generateReplacements())
       if (Result.add(R))
-        return Result;
-    return Result;
+        return std::make_pair(Result, 0);
+    return std::make_pair(Result, Penalty);
   }
 
 private:
-
   static bool inputUsesCRLF(StringRef Text) {
     return Text.count('\r') * 2 > Text.count('\n');
   }
@@ -1082,7 +1126,7 @@ public:
         DeletedTokens(FormatTokenLess(Env.getSourceManager())) {}
 
   // FIXME: eliminate unused parameters.
-  tooling::Replacements
+  std::pair<tooling::Replacements, unsigned>
   analyze(TokenAnnotator &Annotator,
           SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
           FormatTokenLexer &Tokens) override {
@@ -1110,7 +1154,7 @@ public:
       }
     }
 
-    return generateFixes();
+    return {generateFixes(), 0};
   }
 
 private:
@@ -1386,19 +1430,27 @@ static void sortCppIncludes(const FormatStyle &Style,
                             }),
                 Indices.end());
 
+  int CurrentCategory = Includes.front().Category;
+
   // If the #includes are out of order, we generate a single replacement fixing
   // the entire block. Otherwise, no replacement is generated.
   if (Indices.size() == Includes.size() &&
-      std::is_sorted(Indices.begin(), Indices.end()))
+      std::is_sorted(Indices.begin(), Indices.end()) &&
+      Style.IncludeBlocks == FormatStyle::IBS_Preserve)
     return;
 
   std::string result;
   for (unsigned Index : Indices) {
-    if (!result.empty())
+    if (!result.empty()) {
       result += "\n";
+      if (Style.IncludeBlocks == FormatStyle::IBS_Regroup &&
+          CurrentCategory != Includes[Index].Category)
+        result += "\n";
+    }
     result += Includes[Index].Text;
     if (Cursor && CursorIndex == Index)
       *Cursor = IncludesBeginOffset + result.size() - CursorToEOLOffset;
+    CurrentCategory = Includes[Index].Category;
   }
 
   auto Err = Replaces.add(tooling::Replacement(
@@ -1506,6 +1558,10 @@ tooling::Replacements sortCppIncludes(const FormatStyle &Style, StringRef Code,
     else if (Trimmed == "// clang-format on")
       FormattingOff = false;
 
+    const bool EmptyLineSkipped =
+        Trimmed.empty() && (Style.IncludeBlocks == FormatStyle::IBS_Merge ||
+                            Style.IncludeBlocks == FormatStyle::IBS_Regroup);
+
     if (!FormattingOff && !Line.endswith("\\")) {
       if (IncludeRegex.match(Line, &Matches)) {
         StringRef IncludeName = Matches[2];
@@ -1515,7 +1571,7 @@ tooling::Replacements sortCppIncludes(const FormatStyle &Style, StringRef Code,
         if (Category == 0)
           MainIncludeFound = true;
         IncludesInBlock.push_back({IncludeName, Line, Prev, Category});
-      } else if (!IncludesInBlock.empty()) {
+      } else if (!IncludesInBlock.empty() && !EmptyLineSkipped) {
         sortCppIncludes(Style, IncludesInBlock, Ranges, FileName, Replaces,
                         Cursor);
         IncludesInBlock.clear();
@@ -1539,12 +1595,16 @@ bool isMpegTS(StringRef Code) {
   return Code.size() > 188 && Code[0] == 0x47 && Code[188] == 0x47;
 }
 
+bool isLikelyXml(StringRef Code) { return Code.ltrim().startswith("<"); }
+
 tooling::Replacements sortIncludes(const FormatStyle &Style, StringRef Code,
                                    ArrayRef<tooling::Range> Ranges,
                                    StringRef FileName, unsigned *Cursor) {
   tooling::Replacements Replaces;
   if (!Style.SortIncludes)
     return Replaces;
+  if (isLikelyXml(Code))
+    return Replaces;
   if (Style.Language == FormatStyle::LanguageKind::LK_JavaScript &&
       isMpegTS(Code))
     return Replaces;
@@ -1887,17 +1947,22 @@ cleanupAroundReplacements(StringRef Code, const tooling::Replacements &Replaces,
   return processReplacements(Cleanup, Code, NewReplaces, Style);
 }
 
-tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
-                               ArrayRef<tooling::Range> Ranges,
-                               StringRef FileName,
-                               FormattingAttemptStatus *Status) {
+namespace internal {
+std::pair<tooling::Replacements, unsigned>
+reformat(const FormatStyle &Style, StringRef Code,
+         ArrayRef<tooling::Range> Ranges, unsigned FirstStartColumn,
+         unsigned NextStartColumn, unsigned LastStartColumn, StringRef FileName,
+         FormattingAttemptStatus *Status) {
   FormatStyle Expanded = expandPresets(Style);
   if (Expanded.DisableFormat)
-    return tooling::Replacements();
+    return {tooling::Replacements(), 0};
+  if (isLikelyXml(Code))
+    return {tooling::Replacements(), 0};
   if (Expanded.Language == FormatStyle::LK_JavaScript && isMpegTS(Code))
-    return tooling::Replacements();
+    return {tooling::Replacements(), 0};
 
-  typedef std::function<tooling::Replacements(const Environment &)>
+  typedef std::function<std::pair<tooling::Replacements, unsigned>(
+      const Environment &)>
       AnalyzerPass;
   SmallVector<AnalyzerPass, 4> Passes;
 
@@ -1923,26 +1988,42 @@ tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
     return Formatter(Env, Expanded, Status).process();
   });
 
-  std::unique_ptr<Environment> Env =
-      Environment::CreateVirtualEnvironment(Code, FileName, Ranges);
+  std::unique_ptr<Environment> Env = Environment::CreateVirtualEnvironment(
+      Code, FileName, Ranges, FirstStartColumn, NextStartColumn,
+      LastStartColumn);
   llvm::Optional<std::string> CurrentCode = None;
   tooling::Replacements Fixes;
+  unsigned Penalty = 0;
   for (size_t I = 0, E = Passes.size(); I < E; ++I) {
-    tooling::Replacements PassFixes = Passes[I](*Env);
+    std::pair<tooling::Replacements, unsigned> PassFixes = Passes[I](*Env);
     auto NewCode = applyAllReplacements(
-        CurrentCode ? StringRef(*CurrentCode) : Code, PassFixes);
+        CurrentCode ? StringRef(*CurrentCode) : Code, PassFixes.first);
     if (NewCode) {
-      Fixes = Fixes.merge(PassFixes);
+      Fixes = Fixes.merge(PassFixes.first);
+      Penalty += PassFixes.second;
       if (I + 1 < E) {
         CurrentCode = std::move(*NewCode);
         Env = Environment::CreateVirtualEnvironment(
             *CurrentCode, FileName,
-            tooling::calculateRangesAfterReplacements(Fixes, Ranges));
+            tooling::calculateRangesAfterReplacements(Fixes, Ranges),
+            FirstStartColumn, NextStartColumn, LastStartColumn);
       }
     }
   }
 
-  return Fixes;
+  return {Fixes, Penalty};
+}
+} // namespace internal
+
+tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
+                               ArrayRef<tooling::Range> Ranges,
+                               StringRef FileName,
+                               FormattingAttemptStatus *Status) {
+  return internal::reformat(Style, Code, Ranges,
+                            /*FirstStartColumn=*/0,
+                            /*NextStartColumn=*/0,
+                            /*LastStartColumn=*/0, FileName, Status)
+      .first;
 }
 
 tooling::Replacements cleanup(const FormatStyle &Style, StringRef Code,
@@ -1954,7 +2035,7 @@ tooling::Replacements cleanup(const FormatStyle &Style, StringRef Code,
   std::unique_ptr<Environment> Env =
       Environment::CreateVirtualEnvironment(Code, FileName, Ranges);
   Cleaner Clean(*Env, Style);
-  return Clean.process();
+  return Clean.process().first;
 }
 
 tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
@@ -1974,7 +2055,7 @@ tooling::Replacements fixNamespaceEndComments(const FormatStyle &Style,
   std::unique_ptr<Environment> Env =
       Environment::CreateVirtualEnvironment(Code, FileName, Ranges);
   NamespaceEndCommentsFixer Fix(*Env, Style);
-  return Fix.process();
+  return Fix.process().first;
 }
 
 tooling::Replacements sortUsingDeclarations(const FormatStyle &Style,
@@ -1984,7 +2065,7 @@ tooling::Replacements sortUsingDeclarations(const FormatStyle &Style,
   std::unique_ptr<Environment> Env =
       Environment::CreateVirtualEnvironment(Code, FileName, Ranges);
   UsingDeclarationsSorter Sorter(*Env, Style);
-  return Sorter.process();
+  return Sorter.process().first;
 }
 
 LangOptions getFormattingLangOpts(const FormatStyle &Style) {
@@ -1992,7 +2073,8 @@ LangOptions getFormattingLangOpts(const FormatStyle &Style) {
   LangOpts.CPlusPlus = 1;
   LangOpts.CPlusPlus11 = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
   LangOpts.CPlusPlus14 = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
-  LangOpts.CPlusPlus1z = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
+  LangOpts.CPlusPlus17 = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
+  LangOpts.CPlusPlus2a = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
   LangOpts.LineComment = 1;
   bool AlternativeOperators = Style.isCpp();
   LangOpts.CXXOperatorNames = AlternativeOperators ? 1 : 0;
@@ -2025,6 +2107,11 @@ static FormatStyle::LanguageKind getLanguageByFileName(StringRef FileName) {
   if (FileName.endswith_lower(".proto") ||
       FileName.endswith_lower(".protodevel"))
     return FormatStyle::LK_Proto;
+  if (FileName.endswith_lower(".textpb") ||
+      FileName.endswith_lower(".pb.txt") ||
+      FileName.endswith_lower(".textproto") ||
+      FileName.endswith_lower(".asciipb"))
+    return FormatStyle::LK_TextProto;
   if (FileName.endswith_lower(".td"))
     return FormatStyle::LK_TableGen;
   return FormatStyle::LK_Cpp;
@@ -2043,7 +2130,9 @@ llvm::Expected<FormatStyle> getStyle(StringRef StyleName, StringRef FileName,
   // should be improved over time and probably be done on tokens, not one the
   // bare content of the file.
   if (Style.Language == FormatStyle::LK_Cpp && FileName.endswith(".h") &&
-      (Code.contains("\n- (") || Code.contains("\n+ (")))
+      (Code.contains("\n- (") || Code.contains("\n+ (") ||
+       Code.contains("\n@end\n") || Code.contains("\n@end ") ||
+       Code.endswith("@end")))
     Style.Language = FormatStyle::LK_ObjC;
 
   FormatStyle FallbackStyle = getNoStyle();
diff --git a/lib/Format/FormatInternal.h b/lib/Format/FormatInternal.h
new file mode 100644
index 000000000000..3984158467b3
--- /dev/null
+++ b/lib/Format/FormatInternal.h
@@ -0,0 +1,83 @@
+//===--- FormatInternal.h - Format C++ code ---------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file declares Format APIs to be used internally by the
+/// formatting library implementation.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_FORMAT_FORMATINTERNAL_H
+#define LLVM_CLANG_LIB_FORMAT_FORMATINTERNAL_H
+
+#include "BreakableToken.h"
+#include "clang/Tooling/Core/Lookup.h"
+#include <utility>
+
+namespace clang {
+namespace format {
+namespace internal {
+
+/// \brief Reformats the given \p Ranges in the code fragment \p Code.
+///
+/// A fragment of code could conceptually be surrounded by other code that might
+/// constrain how that fragment is laid out.
+/// For example, consider the fragment of code between 'R"(' and ')"',
+/// exclusive, in the following code:
+///
+/// void outer(int x) {
+///   string inner = R"(name: data
+///                     ^ FirstStartColumn
+///     value: {
+///       x: 1
+///     ^ NextStartColumn
+///     }
+///   )";
+///   ^ LastStartColumn
+/// }
+///
+/// The outer code can influence the inner fragment as follows:
+///   * \p FirstStartColumn specifies the column at which \p Code starts.
+///   * \p NextStartColumn specifies the additional indent dictated by the
+///     surrounding code. It is applied to the rest of the lines of \p Code.
+///   * \p LastStartColumn specifies the column at which the last line of
+///     \p Code should end, in case the last line is an empty line.
+///
+///     In the case where the last line of the fragment contains content,
+///     the fragment ends at the end of that content and \p LastStartColumn is
+///     not taken into account, for example in:
+///
+///     void block() {
+///       string inner = R"(name: value)";
+///     }
+///
+/// Each range is extended on either end to its next bigger logic unit, i.e.
+/// everything that might influence its formatting or might be influenced by its
+/// formatting.
+///
+/// Returns a pair P, where:
+///   * P.first are the ``Replacements`` necessary to make all \p Ranges comply
+///     with \p Style.
+///   * P.second is the penalty induced by formatting the fragment \p Code.
+///     If the formatting of the fragment doesn't have a notion of penalty,
+///     returns 0.
+///
+/// If ``Status`` is non-null, its value will be populated with the status of
+/// this formatting attempt. See \c FormattingAttemptStatus.
+std::pair<tooling::Replacements, unsigned>
+reformat(const FormatStyle &Style, StringRef Code,
+         ArrayRef<tooling::Range> Ranges, unsigned FirstStartColumn,
+         unsigned NextStartColumn, unsigned LastStartColumn, StringRef FileName,
+         FormattingAttemptStatus *Status);
+
+} // namespace internal
+} // namespace format
+} // namespace clang
+
+#endif
diff --git a/lib/Format/FormatToken.cpp b/lib/Format/FormatToken.cpp
index ba5bf03a6346..10ac392abbf2 100644
--- a/lib/Format/FormatToken.cpp
+++ b/lib/Format/FormatToken.cpp
@@ -25,10 +25,9 @@ namespace format {
 const char *getTokenTypeName(TokenType Type) {
   static const char *const TokNames[] = {
 #define TYPE(X) #X,
-LIST_TOKEN_TYPES
+      LIST_TOKEN_TYPES
 #undef TYPE
-    nullptr
-  };
+      nullptr};
 
   if (Type < NUM_TOKEN_TYPES)
     return TokNames[Type];
@@ -52,6 +51,7 @@ bool FormatToken::isSimpleTypeSpecifier() const {
   case tok::kw_half:
   case tok::kw_float:
   case tok::kw_double:
+  case tok::kw__Float16:
   case tok::kw___float128:
   case tok::kw_wchar_t:
   case tok::kw_bool:
diff --git a/lib/Format/FormatToken.h b/lib/Format/FormatToken.h
index a60361a8e5fa..3dc0ab0e7cca 100644
--- a/lib/Format/FormatToken.h
+++ b/lib/Format/FormatToken.h
@@ -26,78 +26,79 @@
 namespace clang {
 namespace format {
 
-#define LIST_TOKEN_TYPES \
-  TYPE(ArrayInitializerLSquare) \
-  TYPE(ArraySubscriptLSquare) \
-  TYPE(AttributeParen) \
-  TYPE(BinaryOperator) \
-  TYPE(BitFieldColon) \
-  TYPE(BlockComment) \
-  TYPE(CastRParen) \
-  TYPE(ConditionalExpr) \
-  TYPE(ConflictAlternative) \
-  TYPE(ConflictEnd) \
-  TYPE(ConflictStart) \
-  TYPE(CtorInitializerColon) \
-  TYPE(CtorInitializerComma) \
-  TYPE(DesignatedInitializerLSquare) \
-  TYPE(DesignatedInitializerPeriod) \
-  TYPE(DictLiteral) \
-  TYPE(ForEachMacro) \
-  TYPE(FunctionAnnotationRParen) \
-  TYPE(FunctionDeclarationName) \
-  TYPE(FunctionLBrace) \
-  TYPE(FunctionTypeLParen) \
-  TYPE(ImplicitStringLiteral) \
-  TYPE(InheritanceColon) \
-  TYPE(InheritanceComma) \
-  TYPE(InlineASMBrace) \
-  TYPE(InlineASMColon) \
-  TYPE(JavaAnnotation) \
-  TYPE(JsComputedPropertyName) \
-  TYPE(JsExponentiation) \
-  TYPE(JsExponentiationEqual) \
-  TYPE(JsFatArrow) \
-  TYPE(JsNonNullAssertion) \
-  TYPE(JsTypeColon) \
-  TYPE(JsTypeOperator) \
-  TYPE(JsTypeOptionalQuestion) \
-  TYPE(LambdaArrow) \
-  TYPE(LambdaLSquare) \
-  TYPE(LeadingJavaAnnotation) \
-  TYPE(LineComment) \
-  TYPE(MacroBlockBegin) \
-  TYPE(MacroBlockEnd) \
-  TYPE(ObjCBlockLBrace) \
-  TYPE(ObjCBlockLParen) \
-  TYPE(ObjCDecl) \
-  TYPE(ObjCForIn) \
-  TYPE(ObjCMethodExpr) \
-  TYPE(ObjCMethodSpecifier) \
-  TYPE(ObjCProperty) \
-  TYPE(ObjCStringLiteral) \
-  TYPE(OverloadedOperator) \
-  TYPE(OverloadedOperatorLParen) \
-  TYPE(PointerOrReference) \
-  TYPE(PureVirtualSpecifier) \
-  TYPE(RangeBasedForLoopColon) \
-  TYPE(RegexLiteral) \
-  TYPE(SelectorName) \
-  TYPE(StartOfName) \
-  TYPE(TemplateCloser) \
-  TYPE(TemplateOpener) \
-  TYPE(TemplateString) \
-  TYPE(TrailingAnnotation) \
-  TYPE(TrailingReturnArrow) \
-  TYPE(TrailingUnaryOperator) \
-  TYPE(UnaryOperator) \
+#define LIST_TOKEN_TYPES                                                       \
+  TYPE(ArrayInitializerLSquare)                                                \
+  TYPE(ArraySubscriptLSquare)                                                  \
+  TYPE(AttributeParen)                                                         \
+  TYPE(BinaryOperator)                                                         \
+  TYPE(BitFieldColon)                                                          \
+  TYPE(BlockComment)                                                           \
+  TYPE(CastRParen)                                                             \
+  TYPE(ConditionalExpr)                                                        \
+  TYPE(ConflictAlternative)                                                    \
+  TYPE(ConflictEnd)                                                            \
+  TYPE(ConflictStart)                                                          \
+  TYPE(CtorInitializerColon)                                                   \
+  TYPE(CtorInitializerComma)                                                   \
+  TYPE(DesignatedInitializerLSquare)                                           \
+  TYPE(DesignatedInitializerPeriod)                                            \
+  TYPE(DictLiteral)                                                            \
+  TYPE(ForEachMacro)                                                           \
+  TYPE(FunctionAnnotationRParen)                                               \
+  TYPE(FunctionDeclarationName)                                                \
+  TYPE(FunctionLBrace)                                                         \
+  TYPE(FunctionTypeLParen)                                                     \
+  TYPE(ImplicitStringLiteral)                                                  \
+  TYPE(InheritanceColon)                                                       \
+  TYPE(InheritanceComma)                                                       \
+  TYPE(InlineASMBrace)                                                         \
+  TYPE(InlineASMColon)                                                         \
+  TYPE(JavaAnnotation)                                                         \
+  TYPE(JsComputedPropertyName)                                                 \
+  TYPE(JsExponentiation)                                                       \
+  TYPE(JsExponentiationEqual)                                                  \
+  TYPE(JsFatArrow)                                                             \
+  TYPE(JsNonNullAssertion)                                                     \
+  TYPE(JsTypeColon)                                                            \
+  TYPE(JsTypeOperator)                                                         \
+  TYPE(JsTypeOptionalQuestion)                                                 \
+  TYPE(LambdaArrow)                                                            \
+  TYPE(LambdaLSquare)                                                          \
+  TYPE(LeadingJavaAnnotation)                                                  \
+  TYPE(LineComment)                                                            \
+  TYPE(MacroBlockBegin)                                                        \
+  TYPE(MacroBlockEnd)                                                          \
+  TYPE(ObjCBlockLBrace)                                                        \
+  TYPE(ObjCBlockLParen)                                                        \
+  TYPE(ObjCDecl)                                                               \
+  TYPE(ObjCForIn)                                                              \
+  TYPE(ObjCMethodExpr)                                                         \
+  TYPE(ObjCMethodSpecifier)                                                    \
+  TYPE(ObjCProperty)                                                           \
+  TYPE(ObjCStringLiteral)                                                      \
+  TYPE(OverloadedOperator)                                                     \
+  TYPE(OverloadedOperatorLParen)                                               \
+  TYPE(PointerOrReference)                                                     \
+  TYPE(PureVirtualSpecifier)                                                   \
+  TYPE(RangeBasedForLoopColon)                                                 \
+  TYPE(RegexLiteral)                                                           \
+  TYPE(SelectorName)                                                           \
+  TYPE(StartOfName)                                                            \
+  TYPE(StructuredBindingLSquare)                                               \
+  TYPE(TemplateCloser)                                                         \
+  TYPE(TemplateOpener)                                                         \
+  TYPE(TemplateString)                                                         \
+  TYPE(TrailingAnnotation)                                                     \
+  TYPE(TrailingReturnArrow)                                                    \
+  TYPE(TrailingUnaryOperator)                                                  \
+  TYPE(UnaryOperator)                                                          \
   TYPE(Unknown)
 
 enum TokenType {
 #define TYPE(X) TT_##X,
-LIST_TOKEN_TYPES
+  LIST_TOKEN_TYPES
 #undef TYPE
-  NUM_TOKEN_TYPES
+      NUM_TOKEN_TYPES
 };
 
 /// \brief Determines the name of a token type.
@@ -340,10 +341,11 @@ struct FormatToken {
   bool isSimpleTypeSpecifier() const;
 
   bool isObjCAccessSpecifier() const {
-    return is(tok::at) && Next && (Next->isObjCAtKeyword(tok::objc_public) ||
-                                   Next->isObjCAtKeyword(tok::objc_protected) ||
-                                   Next->isObjCAtKeyword(tok::objc_package) ||
-                                   Next->isObjCAtKeyword(tok::objc_private));
+    return is(tok::at) && Next &&
+           (Next->isObjCAtKeyword(tok::objc_public) ||
+            Next->isObjCAtKeyword(tok::objc_protected) ||
+            Next->isObjCAtKeyword(tok::objc_package) ||
+            Next->isObjCAtKeyword(tok::objc_private));
   }
 
   /// \brief Returns whether \p Tok is ([{ or a template opening <.
@@ -471,6 +473,19 @@ struct FormatToken {
                               Style.Language == FormatStyle::LK_TextProto));
   }
 
+  /// \brief Returns whether the token is the left square bracket of a C++
+  /// structured binding declaration.
+  bool isCppStructuredBinding(const FormatStyle &Style) const {
+    if (!Style.isCpp() || isNot(tok::l_square))
+      return false;
+    const FormatToken *T = this;
+    do {
+      T = T->getPreviousNonComment();
+    } while (T && T->isOneOf(tok::kw_const, tok::kw_volatile, tok::amp,
+                             tok::ampamp));
+    return T && T->is(tok::kw_auto);
+  }
+
   /// \brief Same as opensBlockOrBlockTypeList, but for the closing token.
   bool closesBlockOrBlockTypeList(const FormatStyle &Style) const {
     if (is(TT_TemplateString) && closesScope())
@@ -503,15 +518,13 @@ private:
     return is(K1) && Next && Next->startsSequenceInternal(Tokens...);
   }
 
-  template <typename A>
-  bool startsSequenceInternal(A K1) const {
+  template <typename A> bool startsSequenceInternal(A K1) const {
     if (is(tok::comment) && Next)
       return Next->startsSequenceInternal(K1);
     return is(K1);
   }
 
-  template <typename A, typename... Ts>
-  bool endsSequenceInternal(A K1) const {
+  template <typename A, typename... Ts> bool endsSequenceInternal(A K1) const {
     if (is(tok::comment) && Previous)
       return Previous->endsSequenceInternal(K1);
     return is(K1);
@@ -644,6 +657,7 @@ struct AdditionalKeywords {
     kw_readonly = &IdentTable.get("readonly");
     kw_set = &IdentTable.get("set");
     kw_type = &IdentTable.get("type");
+    kw_typeof = &IdentTable.get("typeof");
     kw_var = &IdentTable.get("var");
     kw_yield = &IdentTable.get("yield");
 
@@ -680,7 +694,7 @@ struct AdditionalKeywords {
     JsExtraKeywords = std::unordered_set<IdentifierInfo *>(
         {kw_as, kw_async, kw_await, kw_declare, kw_finally, kw_from,
          kw_function, kw_get, kw_import, kw_is, kw_let, kw_module, kw_readonly,
-         kw_set, kw_type, kw_var, kw_yield,
+         kw_set, kw_type, kw_typeof, kw_var, kw_yield,
          // Keywords from the Java section.
          kw_abstract, kw_extends, kw_implements, kw_instanceof, kw_interface});
   }
@@ -714,6 +728,7 @@ struct AdditionalKeywords {
   IdentifierInfo *kw_readonly;
   IdentifierInfo *kw_set;
   IdentifierInfo *kw_type;
+  IdentifierInfo *kw_typeof;
   IdentifierInfo *kw_var;
   IdentifierInfo *kw_yield;
 
diff --git a/lib/Format/FormatTokenLexer.cpp b/lib/Format/FormatTokenLexer.cpp
index 45c3ae1afe5f..199d2974c5c7 100644
--- a/lib/Format/FormatTokenLexer.cpp
+++ b/lib/Format/FormatTokenLexer.cpp
@@ -24,10 +24,10 @@ namespace clang {
 namespace format {
 
 FormatTokenLexer::FormatTokenLexer(const SourceManager &SourceMgr, FileID ID,
-                                   const FormatStyle &Style,
+                                   unsigned Column, const FormatStyle &Style,
                                    encoding::Encoding Encoding)
     : FormatTok(nullptr), IsFirstToken(true), StateStack({LexerState::NORMAL}),
-      Column(0), TrailingWhitespace(0), SourceMgr(SourceMgr), ID(ID),
+      Column(Column), TrailingWhitespace(0), SourceMgr(SourceMgr), ID(ID),
       Style(Style), IdentTable(getFormattingLangOpts(Style)),
       Keywords(IdentTable), Encoding(Encoding), FirstInLineIndex(0),
       FormattingDisabled(false), MacroBlockBeginRegex(Style.MacroBlockBegin),
@@ -50,6 +50,8 @@ ArrayRef<FormatToken *> FormatTokenLexer::lex() {
       tryParseJSRegexLiteral();
       handleTemplateStrings();
     }
+    if (Style.Language == FormatStyle::LK_TextProto)
+      tryParsePythonComment();
     tryMergePreviousTokens();
     if (Tokens.back()->NewlinesBefore > 0 || Tokens.back()->IsMultiline)
       FirstInLineIndex = Tokens.size() - 1;
@@ -96,14 +98,8 @@ void FormatTokenLexer::tryMergePreviousTokens() {
   }
 
   if (Style.Language == FormatStyle::LK_Java) {
-    static const tok::TokenKind JavaRightLogicalShift[] = {tok::greater,
-                                                           tok::greater,
-                                                           tok::greater};
-    static const tok::TokenKind JavaRightLogicalShiftAssign[] = {tok::greater,
-                                                                 tok::greater,
-                                                                 tok::greaterequal};
-    if (tryMergeTokens(JavaRightLogicalShift, TT_BinaryOperator))
-      return;
+    static const tok::TokenKind JavaRightLogicalShiftAssign[] = {
+        tok::greater, tok::greater, tok::greaterequal};
     if (tryMergeTokens(JavaRightLogicalShiftAssign, TT_BinaryOperator))
       return;
   }
@@ -162,9 +158,8 @@ bool FormatTokenLexer::tryMergeTokens(ArrayRef<tok::TokenKind> Kinds,
     return false;
   unsigned AddLength = 0;
   for (unsigned i = 1; i < Kinds.size(); ++i) {
-    if (!First[i]->is(Kinds[i]) ||
-        First[i]->WhitespaceRange.getBegin() !=
-            First[i]->WhitespaceRange.getEnd())
+    if (!First[i]->is(Kinds[i]) || First[i]->WhitespaceRange.getBegin() !=
+                                       First[i]->WhitespaceRange.getEnd())
       return false;
     AddLength += First[i]->TokenText.size();
   }
@@ -337,6 +332,27 @@ void FormatTokenLexer::handleTemplateStrings() {
   resetLexer(SourceMgr.getFileOffset(loc));
 }
 
+void FormatTokenLexer::tryParsePythonComment() {
+  FormatToken *HashToken = Tokens.back();
+  if (HashToken->isNot(tok::hash))
+    return;
+  // Turn the remainder of this line into a comment.
+  const char *CommentBegin =
+      Lex->getBufferLocation() - HashToken->TokenText.size(); // at "#"
+  size_t From = CommentBegin - Lex->getBuffer().begin();
+  size_t To = Lex->getBuffer().find_first_of('\n', From);
+  if (To == StringRef::npos)
+    To = Lex->getBuffer().size();
+  size_t Len = To - From;
+  HashToken->Type = TT_LineComment;
+  HashToken->Tok.setKind(tok::comment);
+  HashToken->TokenText = Lex->getBuffer().substr(From, Len);
+  SourceLocation Loc = To < Lex->getBuffer().size()
+                           ? Lex->getSourceLocation(CommentBegin + Len)
+                           : SourceMgr.getLocForEndOfFile(ID);
+  resetLexer(SourceMgr.getFileOffset(Loc));
+}
+
 bool FormatTokenLexer::tryMerge_TMacro() {
   if (Tokens.size() < 4)
     return false;
@@ -529,17 +545,53 @@ FormatToken *FormatTokenLexer::getNextToken() {
     readRawToken(*FormatTok);
   }
 
+  // JavaScript and Java do not allow to escape the end of the line with a
+  // backslash. Backslashes are syntax errors in plain source, but can occur in
+  // comments. When a single line comment ends with a \, it'll cause the next
+  // line of code to be lexed as a comment, breaking formatting. The code below
+  // finds comments that contain a backslash followed by a line break, truncates
+  // the comment token at the backslash, and resets the lexer to restart behind
+  // the backslash.
+  if ((Style.Language == FormatStyle::LK_JavaScript ||
+       Style.Language == FormatStyle::LK_Java) &&
+      FormatTok->is(tok::comment) && FormatTok->TokenText.startswith("//")) {
+    size_t BackslashPos = FormatTok->TokenText.find('\\');
+    while (BackslashPos != StringRef::npos) {
+      if (BackslashPos + 1 < FormatTok->TokenText.size() &&
+          FormatTok->TokenText[BackslashPos + 1] == '\n') {
+        const char *Offset = Lex->getBufferLocation();
+        Offset -= FormatTok->TokenText.size();
+        Offset += BackslashPos + 1;
+        resetLexer(SourceMgr.getFileOffset(Lex->getSourceLocation(Offset)));
+        FormatTok->TokenText = FormatTok->TokenText.substr(0, BackslashPos + 1);
+        FormatTok->ColumnWidth = encoding::columnWidthWithTabs(
+            FormatTok->TokenText, FormatTok->OriginalColumn, Style.TabWidth,
+            Encoding);
+        break;
+      }
+      BackslashPos = FormatTok->TokenText.find('\\', BackslashPos + 1);
+    }
+  }
+
   // In case the token starts with escaped newlines, we want to
   // take them into account as whitespace - this pattern is quite frequent
   // in macro definitions.
   // FIXME: Add a more explicit test.
-  while (FormatTok->TokenText.size() > 1 && FormatTok->TokenText[0] == '\\' &&
-         FormatTok->TokenText[1] == '\n') {
+  while (FormatTok->TokenText.size() > 1 && FormatTok->TokenText[0] == '\\') {
+    unsigned SkippedWhitespace = 0;
+    if (FormatTok->TokenText.size() > 2 &&
+        (FormatTok->TokenText[1] == '\r' && FormatTok->TokenText[2] == '\n'))
+      SkippedWhitespace = 3;
+    else if (FormatTok->TokenText[1] == '\n')
+      SkippedWhitespace = 2;
+    else
+      break;
+
     ++FormatTok->NewlinesBefore;
-    WhitespaceLength += 2;
-    FormatTok->LastNewlineOffset = 2;
+    WhitespaceLength += SkippedWhitespace;
+    FormatTok->LastNewlineOffset = SkippedWhitespace;
     Column = 0;
-    FormatTok->TokenText = FormatTok->TokenText.substr(2);
+    FormatTok->TokenText = FormatTok->TokenText.substr(SkippedWhitespace);
   }
 
   FormatTok->WhitespaceRange = SourceRange(
diff --git a/lib/Format/FormatTokenLexer.h b/lib/Format/FormatTokenLexer.h
index bf10f09cd11e..59dc2a752f1f 100644
--- a/lib/Format/FormatTokenLexer.h
+++ b/lib/Format/FormatTokenLexer.h
@@ -36,7 +36,7 @@ enum LexerState {
 
 class FormatTokenLexer {
 public:
-  FormatTokenLexer(const SourceManager &SourceMgr, FileID ID,
+  FormatTokenLexer(const SourceManager &SourceMgr, FileID ID, unsigned Column,
                    const FormatStyle &Style, encoding::Encoding Encoding);
 
   ArrayRef<FormatToken *> lex();
@@ -73,6 +73,8 @@ private:
   // nested template parts by balancing curly braces.
   void handleTemplateStrings();
 
+  void tryParsePythonComment();
+
   bool tryMerge_TMacro();
 
   bool tryMergeConflictMarkers();
diff --git a/lib/Format/NamespaceEndCommentsFixer.cpp b/lib/Format/NamespaceEndCommentsFixer.cpp
index 85b70b8c0a76..df99bb2e1381 100644
--- a/lib/Format/NamespaceEndCommentsFixer.cpp
+++ b/lib/Format/NamespaceEndCommentsFixer.cpp
@@ -118,6 +118,12 @@ getNamespaceToken(const AnnotatedLine *line,
     return nullptr;
   assert(StartLineIndex < AnnotatedLines.size());
   const FormatToken *NamespaceTok = AnnotatedLines[StartLineIndex]->First;
+  if (NamespaceTok->is(tok::l_brace)) {
+    // "namespace" keyword can be on the line preceding '{', e.g. in styles
+    // where BraceWrapping.AfterNamespace is true.
+    if (StartLineIndex > 0)
+      NamespaceTok = AnnotatedLines[StartLineIndex - 1]->First;
+  }
   // Detect "(inline)? namespace" in the beginning of a line.
   if (NamespaceTok->is(tok::kw_inline))
     NamespaceTok = NamespaceTok->getNextNonComment();
@@ -131,7 +137,7 @@ NamespaceEndCommentsFixer::NamespaceEndCommentsFixer(const Environment &Env,
                                                      const FormatStyle &Style)
     : TokenAnalyzer(Env, Style) {}
 
-tooling::Replacements NamespaceEndCommentsFixer::analyze(
+std::pair<tooling::Replacements, unsigned> NamespaceEndCommentsFixer::analyze(
     TokenAnnotator &Annotator, SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
     FormatTokenLexer &Tokens) {
   const SourceManager &SourceMgr = Env.getSourceManager();
@@ -200,7 +206,7 @@ tooling::Replacements NamespaceEndCommentsFixer::analyze(
     }
     StartLineIndex = SIZE_MAX;
   }
-  return Fixes;
+  return {Fixes, 0};
 }
 
 } // namespace format
diff --git a/lib/Format/NamespaceEndCommentsFixer.h b/lib/Format/NamespaceEndCommentsFixer.h
index 7790668a2e82..4779f0d27c92 100644
--- a/lib/Format/NamespaceEndCommentsFixer.h
+++ b/lib/Format/NamespaceEndCommentsFixer.h
@@ -25,7 +25,7 @@ class NamespaceEndCommentsFixer : public TokenAnalyzer {
 public:
   NamespaceEndCommentsFixer(const Environment &Env, const FormatStyle &Style);
 
-  tooling::Replacements
+  std::pair<tooling::Replacements, unsigned>
   analyze(TokenAnnotator &Annotator,
           SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
           FormatTokenLexer &Tokens) override;
diff --git a/lib/Format/SortJavaScriptImports.cpp b/lib/Format/SortJavaScriptImports.cpp
index e73695ca8477..d0b979e100d5 100644
--- a/lib/Format/SortJavaScriptImports.cpp
+++ b/lib/Format/SortJavaScriptImports.cpp
@@ -123,7 +123,7 @@ public:
       : TokenAnalyzer(Env, Style),
         FileContents(Env.getSourceManager().getBufferData(Env.getFileID())) {}
 
-  tooling::Replacements
+  std::pair<tooling::Replacements, unsigned>
   analyze(TokenAnnotator &Annotator,
           SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
           FormatTokenLexer &Tokens) override {
@@ -138,7 +138,7 @@ public:
         parseModuleReferences(Keywords, AnnotatedLines);
 
     if (References.empty())
-      return Result;
+      return {Result, 0};
 
     SmallVector<unsigned, 16> Indices;
     for (unsigned i = 0, e = References.size(); i != e; ++i)
@@ -168,7 +168,7 @@ public:
     }
 
     if (ReferencesInOrder && SymbolsInOrder)
-      return Result;
+      return {Result, 0};
 
     SourceRange InsertionPoint = References[0].Range;
     InsertionPoint.setEnd(References[References.size() - 1].Range.getEnd());
@@ -202,7 +202,7 @@ public:
       assert(false);
     }
 
-    return Result;
+    return {Result, 0};
   }
 
 private:
@@ -277,7 +277,7 @@ private:
   // Parses module references in the given lines. Returns the module references,
   // and a pointer to the first "main code" line if that is adjacent to the
   // affected lines of module references, nullptr otherwise.
-  std::pair<SmallVector<JsModuleReference, 16>, AnnotatedLine*>
+  std::pair<SmallVector<JsModuleReference, 16>, AnnotatedLine *>
   parseModuleReferences(const AdditionalKeywords &Keywords,
                         SmallVectorImpl<AnnotatedLine *> &AnnotatedLines) {
     SmallVector<JsModuleReference, 16> References;
@@ -413,7 +413,7 @@ private:
       nextToken();
       if (Current->is(tok::r_brace))
         break;
-      if (Current->isNot(tok::identifier))
+      if (!Current->isOneOf(tok::identifier, tok::kw_default))
         return false;
 
       JsImportedSymbol Symbol;
@@ -425,7 +425,7 @@ private:
 
       if (Current->is(Keywords.kw_as)) {
         nextToken();
-        if (Current->isNot(tok::identifier))
+        if (!Current->isOneOf(tok::identifier, tok::kw_default))
           return false;
         Symbol.Alias = Current->TokenText;
         nextToken();
@@ -449,7 +449,7 @@ tooling::Replacements sortJavaScriptImports(const FormatStyle &Style,
   std::unique_ptr<Environment> Env =
       Environment::CreateVirtualEnvironment(Code, FileName, Ranges);
   JavaScriptImportSorter Sorter(*Env, Style);
-  return Sorter.process();
+  return Sorter.process().first;
 }
 
 } // end namespace format
diff --git a/lib/Format/TokenAnalyzer.cpp b/lib/Format/TokenAnalyzer.cpp
index f2e4e8ef0819..d1dfb1fea32b 100644
--- a/lib/Format/TokenAnalyzer.cpp
+++ b/lib/Format/TokenAnalyzer.cpp
@@ -38,7 +38,10 @@ namespace format {
 // Code.
 std::unique_ptr<Environment>
 Environment::CreateVirtualEnvironment(StringRef Code, StringRef FileName,
-                                      ArrayRef<tooling::Range> Ranges) {
+                                      ArrayRef<tooling::Range> Ranges,
+                                      unsigned FirstStartColumn,
+                                      unsigned NextStartColumn,
+                                      unsigned LastStartColumn) {
   // This is referenced by `FileMgr` and will be released by `FileMgr` when it
   // is deleted.
   IntrusiveRefCntPtr<vfs::InMemoryFileSystem> InMemoryFileSystem(
@@ -57,8 +60,9 @@ Environment::CreateVirtualEnvironment(StringRef Code, StringRef FileName,
   std::unique_ptr<SourceManager> VirtualSM(
       new SourceManager(*Diagnostics, *FileMgr));
   InMemoryFileSystem->addFile(
-      FileName, 0, llvm::MemoryBuffer::getMemBuffer(
-                       Code, FileName, /*RequiresNullTerminator=*/false));
+      FileName, 0,
+      llvm::MemoryBuffer::getMemBuffer(Code, FileName,
+                                       /*RequiresNullTerminator=*/false));
   FileID ID = VirtualSM->createFileID(FileMgr->getFile(FileName),
                                       SourceLocation(), clang::SrcMgr::C_User);
   assert(ID.isValid());
@@ -69,9 +73,9 @@ Environment::CreateVirtualEnvironment(StringRef Code, StringRef FileName,
     SourceLocation End = Start.getLocWithOffset(Range.getLength());
     CharRanges.push_back(CharSourceRange::getCharRange(Start, End));
   }
-  return llvm::make_unique<Environment>(ID, std::move(FileMgr),
-                                        std::move(VirtualSM),
-                                        std::move(Diagnostics), CharRanges);
+  return llvm::make_unique<Environment>(
+      ID, std::move(FileMgr), std::move(VirtualSM), std::move(Diagnostics),
+      CharRanges, FirstStartColumn, NextStartColumn, LastStartColumn);
 }
 
 TokenAnalyzer::TokenAnalyzer(const Environment &Env, const FormatStyle &Style)
@@ -88,14 +92,16 @@ TokenAnalyzer::TokenAnalyzer(const Environment &Env, const FormatStyle &Style)
                      << "\n");
 }
 
-tooling::Replacements TokenAnalyzer::process() {
+std::pair<tooling::Replacements, unsigned> TokenAnalyzer::process() {
   tooling::Replacements Result;
-  FormatTokenLexer Tokens(Env.getSourceManager(), Env.getFileID(), Style,
-                          Encoding);
+  FormatTokenLexer Tokens(Env.getSourceManager(), Env.getFileID(),
+                          Env.getFirstStartColumn(), Style, Encoding);
 
-  UnwrappedLineParser Parser(Style, Tokens.getKeywords(), Tokens.lex(), *this);
+  UnwrappedLineParser Parser(Style, Tokens.getKeywords(),
+                             Env.getFirstStartColumn(), Tokens.lex(), *this);
   Parser.parse();
   assert(UnwrappedLines.rbegin()->empty());
+  unsigned Penalty = 0;
   for (unsigned Run = 0, RunE = UnwrappedLines.size(); Run + 1 != RunE; ++Run) {
     DEBUG(llvm::dbgs() << "Run " << Run << "...\n");
     SmallVector<AnnotatedLine *, 16> AnnotatedLines;
@@ -106,13 +112,13 @@ tooling::Replacements TokenAnalyzer::process() {
       Annotator.annotate(*AnnotatedLines.back());
     }
 
-    tooling::Replacements RunResult =
+    std::pair<tooling::Replacements, unsigned> RunResult =
         analyze(Annotator, AnnotatedLines, Tokens);
 
     DEBUG({
       llvm::dbgs() << "Replacements for run " << Run << ":\n";
-      for (tooling::Replacements::const_iterator I = RunResult.begin(),
-                                                 E = RunResult.end();
+      for (tooling::Replacements::const_iterator I = RunResult.first.begin(),
+                                                 E = RunResult.first.end();
            I != E; ++I) {
         llvm::dbgs() << I->toString() << "\n";
       }
@@ -120,17 +126,19 @@ tooling::Replacements TokenAnalyzer::process() {
     for (unsigned i = 0, e = AnnotatedLines.size(); i != e; ++i) {
       delete AnnotatedLines[i];
     }
-    for (const auto &R : RunResult) {
+
+    Penalty += RunResult.second;
+    for (const auto &R : RunResult.first) {
       auto Err = Result.add(R);
       // FIXME: better error handling here. For now, simply return an empty
       // Replacements to indicate failure.
       if (Err) {
         llvm::errs() << llvm::toString(std::move(Err)) << "\n";
-        return tooling::Replacements();
+        return {tooling::Replacements(), 0};
       }
     }
   }
-  return Result;
+  return {Result, Penalty};
 }
 
 void TokenAnalyzer::consumeUnwrappedLine(const UnwrappedLine &TheLine) {
diff --git a/lib/Format/TokenAnalyzer.h b/lib/Format/TokenAnalyzer.h
index 78a3d1bc8d9e..96ea00b25ba1 100644
--- a/lib/Format/TokenAnalyzer.h
+++ b/lib/Format/TokenAnalyzer.h
@@ -37,21 +37,37 @@ namespace format {
 class Environment {
 public:
   Environment(SourceManager &SM, FileID ID, ArrayRef<CharSourceRange> Ranges)
-      : ID(ID), CharRanges(Ranges.begin(), Ranges.end()), SM(SM) {}
+      : ID(ID), CharRanges(Ranges.begin(), Ranges.end()), SM(SM),
+      FirstStartColumn(0),
+      NextStartColumn(0),
+      LastStartColumn(0) {}
 
   Environment(FileID ID, std::unique_ptr<FileManager> FileMgr,
               std::unique_ptr<SourceManager> VirtualSM,
               std::unique_ptr<DiagnosticsEngine> Diagnostics,
-              const std::vector<CharSourceRange> &CharRanges)
+              const std::vector<CharSourceRange> &CharRanges,
+              unsigned FirstStartColumn,
+              unsigned NextStartColumn,
+              unsigned LastStartColumn)
       : ID(ID), CharRanges(CharRanges.begin(), CharRanges.end()),
-        SM(*VirtualSM), FileMgr(std::move(FileMgr)),
+        SM(*VirtualSM), 
+        FirstStartColumn(FirstStartColumn),
+        NextStartColumn(NextStartColumn),
+        LastStartColumn(LastStartColumn),
+        FileMgr(std::move(FileMgr)),
         VirtualSM(std::move(VirtualSM)), Diagnostics(std::move(Diagnostics)) {}
 
-  // This sets up an virtual file system with file \p FileName containing \p
-  // Code.
+  // This sets up an virtual file system with file \p FileName containing the
+  // fragment \p Code. Assumes that \p Code starts at \p FirstStartColumn,
+  // that the next lines of \p Code should start at \p NextStartColumn, and
+  // that \p Code should end at \p LastStartColumn if it ends in newline.
+  // See also the documentation of clang::format::internal::reformat.
   static std::unique_ptr<Environment>
   CreateVirtualEnvironment(StringRef Code, StringRef FileName,
-                           ArrayRef<tooling::Range> Ranges);
+                           ArrayRef<tooling::Range> Ranges,
+                           unsigned FirstStartColumn = 0,
+                           unsigned NextStartColumn = 0,
+                           unsigned LastStartColumn = 0);
 
   FileID getFileID() const { return ID; }
 
@@ -59,10 +75,25 @@ public:
 
   const SourceManager &getSourceManager() const { return SM; }
 
+  // Returns the column at which the fragment of code managed by this
+  // environment starts.
+  unsigned getFirstStartColumn() const { return FirstStartColumn; }
+
+  // Returns the column at which subsequent lines of the fragment of code
+  // managed by this environment should start.
+  unsigned getNextStartColumn() const { return NextStartColumn; }
+
+  // Returns the column at which the fragment of code managed by this
+  // environment should end if it ends in a newline.
+  unsigned getLastStartColumn() const { return LastStartColumn; }
+
 private:
   FileID ID;
   SmallVector<CharSourceRange, 8> CharRanges;
   SourceManager &SM;
+  unsigned FirstStartColumn;
+  unsigned NextStartColumn;
+  unsigned LastStartColumn;
 
   // The order of these fields are important - they should be in the same order
   // as they are created in `CreateVirtualEnvironment` so that they can be
@@ -76,10 +107,10 @@ class TokenAnalyzer : public UnwrappedLineConsumer {
 public:
   TokenAnalyzer(const Environment &Env, const FormatStyle &Style);
 
-  tooling::Replacements process();
+  std::pair<tooling::Replacements, unsigned> process();
 
 protected:
-  virtual tooling::Replacements
+  virtual std::pair<tooling::Replacements, unsigned>
   analyze(TokenAnnotator &Annotator,
           SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
           FormatTokenLexer &Tokens) = 0;
diff --git a/lib/Format/TokenAnnotator.cpp b/lib/Format/TokenAnnotator.cpp
index 46ea06b880ed..298c72b002f8 100644
--- a/lib/Format/TokenAnnotator.cpp
+++ b/lib/Format/TokenAnnotator.cpp
@@ -47,7 +47,7 @@ private:
     if (NonTemplateLess.count(CurrentToken->Previous))
       return false;
 
-    const FormatToken& Previous = *CurrentToken->Previous;
+    const FormatToken &Previous = *CurrentToken->Previous;  // The '<'.
     if (Previous.Previous) {
       if (Previous.Previous->Tok.isLiteral())
         return false;
@@ -152,11 +152,11 @@ private:
       // export type X = (...);
       Contexts.back().IsExpression = false;
     } else if (Left->Previous &&
-        (Left->Previous->isOneOf(tok::kw_static_assert, tok::kw_decltype,
-                                 tok::kw_if, tok::kw_while, tok::l_paren,
-                                 tok::comma) ||
-         Left->Previous->endsSequence(tok::kw_constexpr, tok::kw_if) ||
-         Left->Previous->is(TT_BinaryOperator))) {
+               (Left->Previous->isOneOf(tok::kw_static_assert, tok::kw_decltype,
+                                        tok::kw_if, tok::kw_while, tok::l_paren,
+                                        tok::comma) ||
+                Left->Previous->endsSequence(tok::kw_constexpr, tok::kw_if) ||
+                Left->Previous->is(TT_BinaryOperator))) {
       // static_assert, if and while usually contain expressions.
       Contexts.back().IsExpression = true;
     } else if (Style.Language == FormatStyle::LK_JavaScript && Left->Previous &&
@@ -325,8 +325,7 @@ private:
     // In C++, this can happen either in array of templates (foo<int>[10])
     // or when array is a nested template type (unique_ptr<type1<type2>[]>).
     bool CppArrayTemplates =
-        Style.isCpp() && Parent &&
-        Parent->is(TT_TemplateCloser) &&
+        Style.isCpp() && Parent && Parent->is(TT_TemplateCloser) &&
         (Contexts.back().CanBeExpression || Contexts.back().IsExpression ||
          Contexts.back().InTemplateArgument);
 
@@ -343,7 +342,9 @@ private:
     bool ColonFound = false;
 
     unsigned BindingIncrease = 1;
-    if (Left->is(TT_Unknown)) {
+    if (Left->isCppStructuredBinding(Style)) {
+      Left->Type = TT_StructuredBindingLSquare;
+    } else if (Left->is(TT_Unknown)) {
       if (StartsObjCMethodExpr) {
         Left->Type = TT_ObjCMethodExpr;
       } else if (Style.Language == FormatStyle::LK_JavaScript && Parent &&
@@ -372,6 +373,10 @@ private:
 
     ScopedContextCreator ContextCreator(*this, tok::l_square, BindingIncrease);
     Contexts.back().IsExpression = true;
+    if (Style.Language == FormatStyle::LK_JavaScript && Parent &&
+        Parent->is(TT_JsTypeColon))
+      Contexts.back().IsExpression = false;
+
     Contexts.back().ColonIsObjCMethodExpr = StartsObjCMethodExpr;
 
     while (CurrentToken) {
@@ -439,6 +444,9 @@ private:
       Contexts.back().ColonIsDictLiteral = true;
       if (Left->BlockKind == BK_BracedInit)
         Contexts.back().IsExpression = true;
+      if (Style.Language == FormatStyle::LK_JavaScript && Left->Previous &&
+          Left->Previous->is(TT_JsTypeColon))
+        Contexts.back().IsExpression = false;
 
       while (CurrentToken) {
         if (CurrentToken->is(tok::r_brace)) {
@@ -452,6 +460,8 @@ private:
         updateParameterCount(Left, CurrentToken);
         if (CurrentToken->isOneOf(tok::colon, tok::l_brace, tok::less)) {
           FormatToken *Previous = CurrentToken->getPreviousNonComment();
+          if (Previous->is(TT_JsTypeOptionalQuestion))
+            Previous = Previous->getPreviousNonComment();
           if (((CurrentToken->is(tok::colon) &&
                 (!Contexts.back().ColonIsDictLiteral || !Style.isCpp())) ||
                Style.Language == FormatStyle::LK_Proto ||
@@ -531,8 +541,11 @@ private:
              !Line.First->isOneOf(tok::kw_enum, tok::kw_case)) ||
             Contexts.back().ContextKind == tok::l_paren ||  // function params
             Contexts.back().ContextKind == tok::l_square || // array type
+            (!Contexts.back().IsExpression &&
+             Contexts.back().ContextKind == tok::l_brace) || // object type
             (Contexts.size() == 1 &&
              Line.MustBeDeclaration)) { // method/property declaration
+          Contexts.back().IsExpression = false;
           Tok->Type = TT_JsTypeColon;
           break;
         }
@@ -593,7 +606,8 @@ private:
       break;
     case tok::kw_if:
     case tok::kw_while:
-      if (Tok->is(tok::kw_if) && CurrentToken && CurrentToken->is(tok::kw_constexpr))
+      if (Tok->is(tok::kw_if) && CurrentToken &&
+          CurrentToken->is(tok::kw_constexpr))
         next();
       if (CurrentToken && CurrentToken->is(tok::l_paren)) {
         next();
@@ -603,7 +617,9 @@ private:
       break;
     case tok::kw_for:
       if (Style.Language == FormatStyle::LK_JavaScript) {
-        if (Tok->Previous && Tok->Previous->is(tok::period))
+        // x.for and {for: ...}
+        if ((Tok->Previous && Tok->Previous->is(tok::period)) ||
+            (Tok->Next && Tok->Next->is(tok::colon)))
           break;
         // JS' for await ( ...
         if (CurrentToken && CurrentToken->is(Keywords.kw_await))
@@ -619,8 +635,7 @@ private:
       // marks the first l_paren as a OverloadedOperatorLParen. Here, we make
       // the first two parens OverloadedOperators and the second l_paren an
       // OverloadedOperatorLParen.
-      if (Tok->Previous &&
-          Tok->Previous->is(tok::r_paren) &&
+      if (Tok->Previous && Tok->Previous->is(tok::r_paren) &&
           Tok->Previous->MatchingParen &&
           Tok->Previous->MatchingParen->is(TT_OverloadedOperatorLParen)) {
         Tok->Previous->Type = TT_OverloadedOperator;
@@ -643,7 +658,7 @@ private:
       break;
     case tok::l_brace:
       if (Style.Language == FormatStyle::LK_TextProto) {
-        FormatToken *Previous =Tok->getPreviousNonComment();
+        FormatToken *Previous = Tok->getPreviousNonComment();
         if (Previous && Previous->Type != TT_DictLiteral)
           Previous->Type = TT_SelectorName;
       }
@@ -683,7 +698,8 @@ private:
           CurrentToken->Type = TT_PointerOrReference;
         consumeToken();
         if (CurrentToken &&
-            CurrentToken->Previous->isOneOf(TT_BinaryOperator, tok::comma))
+            CurrentToken->Previous->isOneOf(TT_BinaryOperator, TT_UnaryOperator,
+                                            tok::comma))
           CurrentToken->Previous->Type = TT_OverloadedOperator;
       }
       if (CurrentToken) {
@@ -740,8 +756,8 @@ private:
 
   void parseIncludeDirective() {
     if (CurrentToken && CurrentToken->is(tok::less)) {
-     next();
-     while (CurrentToken) {
+      next();
+      while (CurrentToken) {
         // Mark tokens up to the trailing line comments as implicit string
         // literals.
         if (CurrentToken->isNot(tok::comment) &&
@@ -781,9 +797,9 @@ private:
   void parseHasInclude() {
     if (!CurrentToken || !CurrentToken->is(tok::l_paren))
       return;
-    next();  // '('
+    next(); // '('
     parseIncludeDirective();
-    next();  // ')'
+    next(); // ')'
   }
 
   LineType parsePreprocessorDirective() {
@@ -842,7 +858,7 @@ private:
       if (Tok->is(tok::l_paren))
         parseParens();
       else if (Tok->isOneOf(Keywords.kw___has_include,
-                       Keywords.kw___has_include_next))
+                            Keywords.kw___has_include_next))
         parseHasInclude();
     }
     return Type;
@@ -855,7 +871,7 @@ public:
       return parsePreprocessorDirective();
 
     // Directly allow to 'import <string-literal>' to support protocol buffer
-    // definitions (code.google.com/p/protobuf) or missing "#" (either way we
+    // definitions (github.com/google/protobuf) or missing "#" (either way we
     // should not break the line).
     IdentifierInfo *Info = CurrentToken->Tok.getIdentifierInfo();
     if ((Style.Language == FormatStyle::LK_Java &&
@@ -933,11 +949,11 @@ private:
     // FIXME: Closure-library specific stuff should not be hard-coded but be
     // configurable.
     return Tok.TokenText == "goog" && Tok.Next && Tok.Next->is(tok::period) &&
-           Tok.Next->Next && (Tok.Next->Next->TokenText == "module" ||
-                              Tok.Next->Next->TokenText == "provide" ||
-                              Tok.Next->Next->TokenText == "require" ||
-                              Tok.Next->Next->TokenText == "setTestOnly" ||
-                              Tok.Next->Next->TokenText == "forwardDeclare") &&
+           Tok.Next->Next &&
+           (Tok.Next->Next->TokenText == "module" ||
+            Tok.Next->Next->TokenText == "provide" ||
+            Tok.Next->Next->TokenText == "require" ||
+            Tok.Next->Next->TokenText == "forwardDeclare") &&
            Tok.Next->Next->Next && Tok.Next->Next->Next->is(tok::l_paren);
   }
 
@@ -1054,8 +1070,7 @@ private:
                Current.Previous->is(TT_CtorInitializerColon)) {
       Contexts.back().IsExpression = true;
       Contexts.back().InCtorInitializer = true;
-    } else if (Current.Previous &&
-               Current.Previous->is(TT_InheritanceColon)) {
+    } else if (Current.Previous && Current.Previous->is(TT_InheritanceColon)) {
       Contexts.back().InInheritanceList = true;
     } else if (Current.isOneOf(tok::r_paren, tok::greater, tok::comma)) {
       for (FormatToken *Previous = Current.Previous;
@@ -1104,6 +1119,11 @@ private:
                (!Line.MightBeFunctionDecl || Current.NestingLevel != 0)) {
       Contexts.back().FirstStartOfName = &Current;
       Current.Type = TT_StartOfName;
+    } else if (Current.is(tok::semi)) {
+      // Reset FirstStartOfName after finding a semicolon so that a for loop
+      // with multiple increment statements is not confused with a for loop
+      // having multiple variable declarations.
+      Contexts.back().FirstStartOfName = nullptr;
     } else if (Current.isOneOf(tok::kw_auto, tok::kw___auto_type)) {
       AutoFound = true;
     } else if (Current.is(tok::arrow) &&
@@ -1113,10 +1133,10 @@ private:
                Current.NestingLevel == 0) {
       Current.Type = TT_TrailingReturnArrow;
     } else if (Current.isOneOf(tok::star, tok::amp, tok::ampamp)) {
-      Current.Type =
-          determineStarAmpUsage(Current, Contexts.back().CanBeExpression &&
-                                             Contexts.back().IsExpression,
-                                Contexts.back().InTemplateArgument);
+      Current.Type = determineStarAmpUsage(Current,
+                                           Contexts.back().CanBeExpression &&
+                                               Contexts.back().IsExpression,
+                                           Contexts.back().InTemplateArgument);
     } else if (Current.isOneOf(tok::minus, tok::plus, tok::caret)) {
       Current.Type = determinePlusMinusCaretUsage(Current);
       if (Current.is(TT_UnaryOperator) && Current.is(tok::caret))
@@ -1396,11 +1416,13 @@ private:
     if (NextToken->isOneOf(tok::comma, tok::semi))
       return TT_PointerOrReference;
 
-    if (PrevToken->is(tok::r_paren) && PrevToken->MatchingParen &&
-        PrevToken->MatchingParen->Previous &&
-        PrevToken->MatchingParen->Previous->isOneOf(tok::kw_typeof,
-                                                    tok::kw_decltype))
-      return TT_PointerOrReference;
+    if (PrevToken->is(tok::r_paren) && PrevToken->MatchingParen) {
+      FormatToken *TokenBeforeMatchingParen =
+          PrevToken->MatchingParen->getPreviousNonComment();
+      if (TokenBeforeMatchingParen &&
+          TokenBeforeMatchingParen->isOneOf(tok::kw_typeof, tok::kw_decltype))
+        return TT_PointerOrReference;
+    }
 
     if (PrevToken->Tok.isLiteral() ||
         PrevToken->isOneOf(tok::r_paren, tok::r_square, tok::kw_true,
@@ -1589,7 +1611,7 @@ private:
       if (Current->is(TT_ConditionalExpr))
         return prec::Conditional;
       if (NextNonComment && Current->is(TT_SelectorName) &&
-          (NextNonComment->is(TT_DictLiteral) ||
+          (NextNonComment->isOneOf(TT_DictLiteral, TT_JsTypeColon) ||
            ((Style.Language == FormatStyle::LK_Proto ||
              Style.Language == FormatStyle::LK_TextProto) &&
             NextNonComment->is(tok::less))))
@@ -1643,17 +1665,15 @@ private:
   /// \brief Parse unary operator expressions and surround them with fake
   /// parentheses if appropriate.
   void parseUnaryOperator() {
-    if (!Current || Current->isNot(TT_UnaryOperator)) {
-      parse(PrecedenceArrowAndPeriod);
-      return;
+    llvm::SmallVector<FormatToken *, 2> Tokens;
+    while (Current && Current->is(TT_UnaryOperator)) {
+      Tokens.push_back(Current);
+      next();
     }
-
-    FormatToken *Start = Current;
-    next();
-    parseUnaryOperator();
-
-    // The actual precedence doesn't matter.
-    addFakeParenthesis(Start, prec::Unknown);
+    parse(PrecedenceArrowAndPeriod);
+    for (FormatToken *Token : llvm::reverse(Tokens))
+      // The actual precedence doesn't matter.
+      addFakeParenthesis(Token, prec::Unknown);
   }
 
   void parseConditionalExpr() {
@@ -1722,7 +1742,7 @@ void TokenAnnotator::setCommentLineLevels(
 
 static unsigned maxNestingDepth(const AnnotatedLine &Line) {
   unsigned Result = 0;
-  for (const auto* Tok = Line.First; Tok != nullptr; Tok = Tok->Next)
+  for (const auto *Tok = Line.First; Tok != nullptr; Tok = Tok->Next)
     Result = std::max(Result, Tok->NestingLevel);
   return Result;
 }
@@ -1764,7 +1784,7 @@ void TokenAnnotator::annotate(AnnotatedLine &Line) {
 // function declaration.
 static bool isFunctionDeclarationName(const FormatToken &Current,
                                       const AnnotatedLine &Line) {
-  auto skipOperatorName = [](const FormatToken* Next) -> const FormatToken* {
+  auto skipOperatorName = [](const FormatToken *Next) -> const FormatToken * {
     for (; Next; Next = Next->Next) {
       if (Next->is(TT_OverloadedOperatorLParen))
         return Next;
@@ -1772,8 +1792,8 @@ static bool isFunctionDeclarationName(const FormatToken &Current,
         continue;
       if (Next->isOneOf(tok::kw_new, tok::kw_delete)) {
         // For 'new[]' and 'delete[]'.
-        if (Next->Next && Next->Next->is(tok::l_square) &&
-            Next->Next->Next && Next->Next->Next->is(tok::r_square))
+        if (Next->Next && Next->Next->is(tok::l_square) && Next->Next->Next &&
+            Next->Next->Next->is(tok::r_square))
           Next = Next->Next->Next;
         continue;
       }
@@ -1872,7 +1892,8 @@ void TokenAnnotator::calculateFormattingInformation(AnnotatedLine &Line) {
   }
 
   Line.First->TotalLength =
-      Line.First->IsMultiline ? Style.ColumnLimit : Line.First->ColumnWidth;
+      Line.First->IsMultiline ? Style.ColumnLimit
+                              : Line.FirstStartColumn + Line.First->ColumnWidth;
   FormatToken *Current = Line.First->Next;
   bool InFunctionDecl = Line.MightBeFunctionDecl;
   while (Current) {
@@ -2005,6 +2026,9 @@ unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
     if ((Left.is(TT_TemplateString) && Left.TokenText.endswith("${")) ||
         (Right.is(TT_TemplateString) && Right.TokenText.startswith("}")))
       return 100;
+    // Prefer breaking call chains (".foo") over empty "{}", "[]" or "()".
+    if (Left.opensScope() && Right.closesScope())
+      return 200;
   }
 
   if (Right.is(tok::identifier) && Right.Next && Right.Next->is(TT_DictLiteral))
@@ -2049,7 +2073,8 @@ unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
   if (Left.is(tok::comment))
     return 1000;
 
-  if (Left.isOneOf(TT_RangeBasedForLoopColon, TT_InheritanceColon, TT_CtorInitializerColon))
+  if (Left.isOneOf(TT_RangeBasedForLoopColon, TT_InheritanceColon,
+                   TT_CtorInitializerColon))
     return 2;
 
   if (Right.isMemberAccess()) {
@@ -2107,8 +2132,8 @@ unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
       Style.AlignAfterOpenBracket != FormatStyle::BAS_DontAlign)
     return 100;
   if (Left.is(tok::l_paren) && Left.Previous &&
-      (Left.Previous->isOneOf(tok::kw_if, tok::kw_for)
-       || Left.Previous->endsSequence(tok::kw_constexpr, tok::kw_if)))
+      (Left.Previous->isOneOf(tok::kw_if, tok::kw_for) ||
+       Left.Previous->endsSequence(tok::kw_constexpr, tok::kw_if)))
     return 1000;
   if (Left.is(tok::equal) && InFunctionDecl)
     return 110;
@@ -2128,7 +2153,7 @@ unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
   if (Left.isOneOf(tok::plus, tok::comma) && Left.Previous &&
       Left.Previous->isLabelString() &&
       (Left.NextOperator || Left.OperatorIndex != 0))
-    return 45;
+    return 50;
   if (Right.is(tok::plus) && Left.isLabelString() &&
       (Right.NextOperator || Right.OperatorIndex != 0))
     return 25;
@@ -2162,6 +2187,8 @@ bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
                                           const FormatToken &Right) {
   if (Left.is(tok::kw_return) && Right.isNot(tok::semi))
     return true;
+  if (Left.is(Keywords.kw_assert) && Style.Language == FormatStyle::LK_Java)
+    return true;
   if (Style.ObjCSpaceAfterProperty && Line.Type == LT_ObjCProperty &&
       Left.Tok.getObjCKeywordID() == tok::objc_property)
     return true;
@@ -2178,8 +2205,8 @@ bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
                : Style.SpacesInParentheses;
   if (Right.isOneOf(tok::semi, tok::comma))
     return false;
-  if (Right.is(tok::less) &&
-      Line.Type == LT_ObjCDecl && Style.ObjCSpaceBeforeProtocolList)
+  if (Right.is(tok::less) && Line.Type == LT_ObjCDecl &&
+      Style.ObjCSpaceBeforeProtocolList)
     return true;
   if (Right.is(tok::less) && Left.is(tok::kw_template))
     return Style.SpaceAfterTemplateKeyword;
@@ -2201,15 +2228,23 @@ bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
                                     Left.Previous->is(tok::kw_case));
   if (Left.is(tok::l_square) && Right.is(tok::amp))
     return false;
-  if (Right.is(TT_PointerOrReference))
-    return (Left.is(tok::r_paren) && Line.MightBeFunctionDecl) ||
-           (Left.Tok.isLiteral() || (Left.is(tok::kw_const) && Left.Previous &&
-                                     Left.Previous->is(tok::r_paren)) ||
+  if (Right.is(TT_PointerOrReference)) {
+    if (Left.is(tok::r_paren) && Line.MightBeFunctionDecl) {
+      if (!Left.MatchingParen)
+        return true;
+      FormatToken *TokenBeforeMatchingParen =
+          Left.MatchingParen->getPreviousNonComment();
+      if (!TokenBeforeMatchingParen ||
+          !TokenBeforeMatchingParen->isOneOf(tok::kw_typeof, tok::kw_decltype))
+        return true;
+    }
+    return (Left.Tok.isLiteral() ||
             (!Left.isOneOf(TT_PointerOrReference, tok::l_paren) &&
              (Style.PointerAlignment != FormatStyle::PAS_Left ||
               (Line.IsMultiVariableDeclStmt &&
                (Left.NestingLevel == 0 ||
                 (Left.NestingLevel == 1 && Line.First->is(tok::kw_for)))))));
+  }
   if (Right.is(TT_FunctionTypeLParen) && Left.isNot(tok::l_paren) &&
       (!Left.is(TT_PointerOrReference) ||
        (Style.PointerAlignment != FormatStyle::PAS_Right &&
@@ -2231,17 +2266,20 @@ bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
   if (Left.is(tok::l_square))
     return (Left.is(TT_ArrayInitializerLSquare) &&
             Style.SpacesInContainerLiterals && Right.isNot(tok::r_square)) ||
-           (Left.is(TT_ArraySubscriptLSquare) && Style.SpacesInSquareBrackets &&
-            Right.isNot(tok::r_square));
+           (Left.isOneOf(TT_ArraySubscriptLSquare,
+                         TT_StructuredBindingLSquare) &&
+            Style.SpacesInSquareBrackets && Right.isNot(tok::r_square));
   if (Right.is(tok::r_square))
     return Right.MatchingParen &&
            ((Style.SpacesInContainerLiterals &&
              Right.MatchingParen->is(TT_ArrayInitializerLSquare)) ||
             (Style.SpacesInSquareBrackets &&
-             Right.MatchingParen->is(TT_ArraySubscriptLSquare)));
+             Right.MatchingParen->isOneOf(TT_ArraySubscriptLSquare,
+                                          TT_StructuredBindingLSquare)));
   if (Right.is(tok::l_square) &&
       !Right.isOneOf(TT_ObjCMethodExpr, TT_LambdaLSquare,
-                     TT_DesignatedInitializerLSquare) &&
+                     TT_DesignatedInitializerLSquare,
+                     TT_StructuredBindingLSquare) &&
       !Left.isOneOf(tok::numeric_constant, TT_DictLiteral))
     return false;
   if (Left.is(tok::l_brace) && Right.is(tok::r_brace))
@@ -2287,7 +2325,7 @@ bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
   if (Left.is(TT_TemplateCloser) && Left.MatchingParen &&
       Left.MatchingParen->Previous &&
       Left.MatchingParen->Previous->is(tok::period))
-    // A.<B>DoSomething();
+    // A.<B<C<...>>>DoSomething();
     return false;
   if (Left.is(TT_TemplateCloser) && Right.is(tok::l_square))
     return false;
@@ -2317,8 +2355,8 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
     if (Left.is(TT_JsFatArrow))
       return true;
     // for await ( ...
-    if (Right.is(tok::l_paren) && Left.is(Keywords.kw_await) &&
-        Left.Previous && Left.Previous->is(tok::kw_for))
+    if (Right.is(tok::l_paren) && Left.is(Keywords.kw_await) && Left.Previous &&
+        Left.Previous->is(tok::kw_for))
       return true;
     if (Left.is(Keywords.kw_async) && Right.is(tok::l_paren) &&
         Right.MatchingParen) {
@@ -2341,18 +2379,31 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
         Left.isOneOf(Keywords.kw_function, Keywords.kw_yield))
       return false;
     if (Right.isOneOf(tok::l_brace, tok::l_square) &&
-        Left.isOneOf(Keywords.kw_function, Keywords.kw_yield))
+        Left.isOneOf(Keywords.kw_function, Keywords.kw_yield,
+                     Keywords.kw_extends, Keywords.kw_implements))
       return true;
-    // JS methods can use some keywords as names (e.g. `delete()`).
-    if (Right.is(tok::l_paren) && Line.MustBeDeclaration &&
-        Left.Tok.getIdentifierInfo())
-      return false;
+    if (Right.is(tok::l_paren)) {
+      // JS methods can use some keywords as names (e.g. `delete()`).
+      if (Line.MustBeDeclaration && Left.Tok.getIdentifierInfo())
+        return false;
+      // Valid JS method names can include keywords, e.g. `foo.delete()` or
+      // `bar.instanceof()`. Recognize call positions by preceding period.
+      if (Left.Previous && Left.Previous->is(tok::period) &&
+          Left.Tok.getIdentifierInfo())
+        return false;
+      // Additional unary JavaScript operators that need a space after.
+      if (Left.isOneOf(tok::kw_throw, Keywords.kw_await, Keywords.kw_typeof,
+                       tok::kw_void))
+        return true;
+    }
     if ((Left.isOneOf(Keywords.kw_let, Keywords.kw_var, Keywords.kw_in,
                       tok::kw_const) ||
          // "of" is only a keyword if it appears after another identifier
-         // (e.g. as "const x of y" in a for loop).
+         // (e.g. as "const x of y" in a for loop), or after a destructuring
+         // operation (const [x, y] of z, const {a, b} of c).
          (Left.is(Keywords.kw_of) && Left.Previous &&
-          Left.Previous->Tok.getIdentifierInfo())) &&
+          (Left.Previous->Tok.getIdentifierInfo() ||
+           Left.Previous->isOneOf(tok::r_square, tok::r_brace)))) &&
         (!Left.Previous || !Left.Previous->is(tok::period)))
       return true;
     if (Left.isOneOf(tok::kw_for, Keywords.kw_as) && Left.Previous &&
@@ -2384,8 +2435,9 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
       return false;
     if (Right.is(TT_JsNonNullAssertion))
       return false;
-    if (Left.is(TT_JsNonNullAssertion) && Right.is(Keywords.kw_as))
-      return true; // "x! as string"
+    if (Left.is(TT_JsNonNullAssertion) &&
+        Right.isOneOf(Keywords.kw_as, Keywords.kw_in))
+      return true; // "x! as string", "x! in y"
   } else if (Style.Language == FormatStyle::LK_Java) {
     if (Left.is(tok::r_square) && Right.is(tok::l_brace))
       return true;
@@ -2464,9 +2516,18 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
     return (Left.is(TT_TemplateOpener) &&
             Style.Standard == FormatStyle::LS_Cpp03) ||
            !(Left.isOneOf(tok::l_paren, tok::r_paren, tok::l_square,
-                          tok::kw___super, TT_TemplateCloser, TT_TemplateOpener));
+                          tok::kw___super, TT_TemplateCloser,
+                          TT_TemplateOpener));
   if ((Left.is(TT_TemplateOpener)) != (Right.is(TT_TemplateCloser)))
     return Style.SpacesInAngles;
+  // Space before TT_StructuredBindingLSquare.
+  if (Right.is(TT_StructuredBindingLSquare))
+    return !Left.isOneOf(tok::amp, tok::ampamp) ||
+           Style.PointerAlignment != FormatStyle::PAS_Right;
+  // Space before & or && following a TT_StructuredBindingLSquare.
+  if (Right.Next && Right.Next->is(TT_StructuredBindingLSquare) &&
+      Right.isOneOf(tok::amp, tok::ampamp))
+    return Style.PointerAlignment != FormatStyle::PAS_Left;
   if ((Right.is(TT_BinaryOperator) && !Left.is(tok::l_paren)) ||
       (Left.isOneOf(TT_BinaryOperator, TT_ConditionalExpr) &&
        !Right.is(tok::r_paren)))
@@ -2516,7 +2577,9 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
       return true;
     if (Left.is(tok::l_brace) && Line.Level == 0 &&
         (Line.startsWith(tok::kw_enum) ||
-         Line.startsWith(tok::kw_export, tok::kw_enum)))
+         Line.startsWith(tok::kw_const, tok::kw_enum) ||
+         Line.startsWith(tok::kw_export, tok::kw_enum) ||
+         Line.startsWith(tok::kw_export, tok::kw_const, tok::kw_enum)))
       // JavaScript top-level enum key/value pairs are put on separate lines
       // instead of bin-packing.
       return true;
@@ -2587,19 +2650,16 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
       !Style.ConstructorInitializerAllOnOneLineOrOnePerLine)
     return true;
   // Break only if we have multiple inheritance.
-  if (Style.BreakBeforeInheritanceComma &&
-      Right.is(TT_InheritanceComma))
-   return true;
+  if (Style.BreakBeforeInheritanceComma && Right.is(TT_InheritanceComma))
+    return true;
   if (Right.is(tok::string_literal) && Right.TokenText.startswith("R\""))
     // Raw string literals are special wrt. line breaks. The author has made a
     // deliberate choice and might have aligned the contents of the string
     // literal accordingly. Thus, we try keep existing line breaks.
     return Right.NewlinesBefore > 0;
   if ((Right.Previous->is(tok::l_brace) ||
-       (Right.Previous->is(tok::less) &&
-        Right.Previous->Previous &&
-        Right.Previous->Previous->is(tok::equal))
-        ) &&
+       (Right.Previous->is(tok::less) && Right.Previous->Previous &&
+        Right.Previous->Previous->is(tok::equal))) &&
       Right.NestingLevel == 1 && Style.Language == FormatStyle::LK_Proto) {
     // Don't put enums or option definitions onto single lines in protocol
     // buffers.
@@ -2609,6 +2669,8 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
     return Right.HasUnescapedNewline;
   if (isAllmanBrace(Left) || isAllmanBrace(Right))
     return (Line.startsWith(tok::kw_enum) && Style.BraceWrapping.AfterEnum) ||
+           (Line.startsWith(tok::kw_typedef, tok::kw_enum) &&
+            Style.BraceWrapping.AfterEnum) ||
            (Line.startsWith(tok::kw_class) && Style.BraceWrapping.AfterClass) ||
            (Line.startsWith(tok::kw_struct) && Style.BraceWrapping.AfterStruct);
   if (Left.is(TT_ObjCBlockLBrace) && !Style.AllowShortBlocksOnASingleLine)
@@ -2639,13 +2701,16 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
   } else if (Style.Language == FormatStyle::LK_JavaScript) {
     const FormatToken *NonComment = Right.getPreviousNonComment();
     if (NonComment &&
-        NonComment->isOneOf(tok::kw_return, tok::kw_continue, tok::kw_break,
-                            tok::kw_throw, Keywords.kw_interface,
-                            Keywords.kw_type, tok::kw_static, tok::kw_public,
-                            tok::kw_private, tok::kw_protected,
-                            Keywords.kw_readonly, Keywords.kw_abstract,
-                            Keywords.kw_get, Keywords.kw_set))
+        NonComment->isOneOf(
+            tok::kw_return, Keywords.kw_yield, tok::kw_continue, tok::kw_break,
+            tok::kw_throw, Keywords.kw_interface, Keywords.kw_type,
+            tok::kw_static, tok::kw_public, tok::kw_private, tok::kw_protected,
+            Keywords.kw_readonly, Keywords.kw_abstract, Keywords.kw_get,
+            Keywords.kw_set, Keywords.kw_async, Keywords.kw_await))
       return false; // Otherwise automatic semicolon insertion would trigger.
+    if (Left.Tok.getIdentifierInfo() &&
+        Right.startsSequence(tok::l_square, tok::r_square))
+      return false;  // breaking in "foo[]" creates illegal TS type syntax.
     if (Left.is(TT_JsFatArrow) && Right.is(tok::l_brace))
       return false;
     if (Left.is(TT_JsTypeColon))
@@ -2702,8 +2767,7 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
     // list.
     return Left.BlockKind == BK_BracedInit ||
            (Left.is(TT_CtorInitializerColon) &&
-            Style.BreakConstructorInitializers ==
-                FormatStyle::BCIS_AfterColon);
+            Style.BreakConstructorInitializers == FormatStyle::BCIS_AfterColon);
   if (Left.is(tok::question) && Right.is(tok::colon))
     return false;
   if (Right.is(TT_ConditionalExpr) || Right.is(tok::question))
@@ -2820,7 +2884,7 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
 }
 
 void TokenAnnotator::printDebugInfo(const AnnotatedLine &Line) {
-  llvm::errs() << "AnnotatedTokens:\n";
+  llvm::errs() << "AnnotatedTokens(L=" << Line.Level << "):\n";
   const FormatToken *Tok = Line.First;
   while (Tok) {
     llvm::errs() << " M=" << Tok->MustBreakBefore
@@ -2828,10 +2892,9 @@ void TokenAnnotator::printDebugInfo(const AnnotatedLine &Line) {
                  << " T=" << getTokenTypeName(Tok->Type)
                  << " S=" << Tok->SpacesRequiredBefore
                  << " B=" << Tok->BlockParameterCount
-                 << " BK=" << Tok->BlockKind
-                 << " P=" << Tok->SplitPenalty << " Name=" << Tok->Tok.getName()
-                 << " L=" << Tok->TotalLength << " PPK=" << Tok->PackingKind
-                 << " FakeLParens=";
+                 << " BK=" << Tok->BlockKind << " P=" << Tok->SplitPenalty
+                 << " Name=" << Tok->Tok.getName() << " L=" << Tok->TotalLength
+                 << " PPK=" << Tok->PackingKind << " FakeLParens=";
     for (unsigned i = 0, e = Tok->FakeLParens.size(); i != e; ++i)
       llvm::errs() << Tok->FakeLParens[i] << "/";
     llvm::errs() << " FakeRParens=" << Tok->FakeRParens;
diff --git a/lib/Format/TokenAnnotator.h b/lib/Format/TokenAnnotator.h
index 805509533bf9..04a18d45b82e 100644
--- a/lib/Format/TokenAnnotator.h
+++ b/lib/Format/TokenAnnotator.h
@@ -43,7 +43,8 @@ public:
         InPPDirective(Line.InPPDirective),
         MustBeDeclaration(Line.MustBeDeclaration), MightBeFunctionDecl(false),
         IsMultiVariableDeclStmt(false), Affected(false),
-        LeadingEmptyLinesAffected(false), ChildrenAffected(false) {
+        LeadingEmptyLinesAffected(false), ChildrenAffected(false),
+        FirstStartColumn(Line.FirstStartColumn) {
     assert(!Line.Tokens.empty());
 
     // Calculate Next and Previous for all tokens. Note that we must overwrite
@@ -127,6 +128,8 @@ public:
   /// \c True if one of this line's children intersects with an input range.
   bool ChildrenAffected;
 
+  unsigned FirstStartColumn;
+
 private:
   // Disallow copying.
   AnnotatedLine(const AnnotatedLine &) = delete;
diff --git a/lib/Format/UnwrappedLineFormatter.cpp b/lib/Format/UnwrappedLineFormatter.cpp
index 2005a2822924..60dc1a7169d1 100644
--- a/lib/Format/UnwrappedLineFormatter.cpp
+++ b/lib/Format/UnwrappedLineFormatter.cpp
@@ -164,8 +164,7 @@ public:
       return nullptr;
     const AnnotatedLine *Current = *Next;
     IndentTracker.nextLine(*Current);
-    unsigned MergedLines =
-        tryFitMultipleLinesInOne(IndentTracker, Next, End);
+    unsigned MergedLines = tryFitMultipleLinesInOne(IndentTracker, Next, End);
     if (MergedLines > 0 && Style.ColumnLimit == 0)
       // Disallow line merging if there is a break at the start of one of the
       // input lines.
@@ -228,14 +227,16 @@ private:
 
       if (Tok && Tok->getNamespaceToken())
         return !Style.BraceWrapping.SplitEmptyNamespace && EmptyBlock
-            ? tryMergeSimpleBlock(I, E, Limit) : 0;
+                   ? tryMergeSimpleBlock(I, E, Limit)
+                   : 0;
 
       if (Tok && Tok->is(tok::kw_typedef))
         Tok = Tok->getNextNonComment();
       if (Tok && Tok->isOneOf(tok::kw_class, tok::kw_struct, tok::kw_union,
-                              Keywords.kw_interface))
+                              tok::kw_extern, Keywords.kw_interface))
         return !Style.BraceWrapping.SplitEmptyRecord && EmptyBlock
-            ? tryMergeSimpleBlock(I, E, Limit) : 0;
+                   ? tryMergeSimpleBlock(I, E, Limit)
+                   : 0;
     }
 
     // FIXME: TheLine->Level != 0 might or might not be the right check to do.
@@ -279,15 +280,43 @@ private:
       }
     }
 
+    // Try to merge a function block with left brace unwrapped
     if (TheLine->Last->is(TT_FunctionLBrace) &&
         TheLine->First != TheLine->Last) {
       return MergeShortFunctions ? tryMergeSimpleBlock(I, E, Limit) : 0;
     }
+    // Try to merge a control statement block with left brace unwrapped
+    if (TheLine->Last->is(tok::l_brace) && TheLine->First != TheLine->Last &&
+        TheLine->First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_for)) {
+      return Style.AllowShortBlocksOnASingleLine
+                 ? tryMergeSimpleBlock(I, E, Limit)
+                 : 0;
+    }
+    // Try to merge a control statement block with left brace wrapped
+    if (I[1]->First->is(tok::l_brace) &&
+        TheLine->First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_for)) {
+      return Style.BraceWrapping.AfterControlStatement
+                 ? tryMergeSimpleBlock(I, E, Limit)
+                 : 0;
+    }
+    // Try to merge either empty or one-line block if is precedeed by control
+    // statement token
+    if (TheLine->First->is(tok::l_brace) && TheLine->First == TheLine->Last &&
+        I != AnnotatedLines.begin() &&
+        I[-1]->First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_for)) {
+      return Style.AllowShortBlocksOnASingleLine
+                 ? tryMergeSimpleBlock(I - 1, E, Limit)
+                 : 0;
+    }
+    // Try to merge a block with left brace wrapped that wasn't yet covered
     if (TheLine->Last->is(tok::l_brace)) {
-      return !Style.BraceWrapping.AfterFunction
+      return !Style.BraceWrapping.AfterFunction ||
+                     (I[1]->First->is(tok::r_brace) &&
+                      !Style.BraceWrapping.SplitEmptyRecord)
                  ? tryMergeSimpleBlock(I, E, Limit)
                  : 0;
     }
+    // Try to merge a function block with left brace wrapped
     if (I[1]->First->is(TT_FunctionLBrace) &&
         Style.BraceWrapping.AfterFunction) {
       if (I[1]->Last->is(TT_LineComment))
@@ -382,7 +411,9 @@ private:
       return 0;
     unsigned NumStmts = 0;
     unsigned Length = 0;
+    bool EndsWithComment = false;
     bool InPPDirective = I[0]->InPPDirective;
+    const unsigned Level = I[0]->Level;
     for (; NumStmts < 3; ++NumStmts) {
       if (I + 1 + NumStmts == E)
         break;
@@ -392,9 +423,26 @@ private:
       if (Line->First->isOneOf(tok::kw_case, tok::kw_default, tok::r_brace))
         break;
       if (Line->First->isOneOf(tok::kw_if, tok::kw_for, tok::kw_switch,
-                               tok::kw_while, tok::comment) ||
-          Line->Last->is(tok::comment))
+                               tok::kw_while) ||
+          EndsWithComment)
         return 0;
+      if (Line->First->is(tok::comment)) {
+        if (Level != Line->Level)
+          return 0;
+        SmallVectorImpl<AnnotatedLine *>::const_iterator J = I + 2 + NumStmts;
+        for (; J != E; ++J) {
+          Line = *J;
+          if (Line->InPPDirective != InPPDirective)
+            break;
+          if (Line->First->isOneOf(tok::kw_case, tok::kw_default, tok::r_brace))
+            break;
+          if (Line->First->isNot(tok::comment) || Level != Line->Level)
+            return 0;
+        }
+        break;
+      }
+      if (Line->Last->is(tok::comment))
+        EndsWithComment = true;
       Length += I[1 + NumStmts]->Last->TotalLength + 1; // 1 for the space.
     }
     if (NumStmts == 0 || NumStmts == 3 || Length > Limit)
@@ -425,11 +473,27 @@ private:
                             tok::kw_for, tok::r_brace, Keywords.kw___except)) {
       if (!Style.AllowShortBlocksOnASingleLine)
         return 0;
+      // Don't merge when we can't except the case when
+      // the control statement block is empty
       if (!Style.AllowShortIfStatementsOnASingleLine &&
-          Line.startsWith(tok::kw_if))
+          Line.startsWith(tok::kw_if) &&
+          !Style.BraceWrapping.AfterControlStatement &&
+          !I[1]->First->is(tok::r_brace))
+        return 0;
+      if (!Style.AllowShortIfStatementsOnASingleLine &&
+          Line.startsWith(tok::kw_if) &&
+          Style.BraceWrapping.AfterControlStatement && I + 2 != E &&
+          !I[2]->First->is(tok::r_brace))
+        return 0;
+      if (!Style.AllowShortLoopsOnASingleLine &&
+          Line.First->isOneOf(tok::kw_while, tok::kw_do, tok::kw_for) &&
+          !Style.BraceWrapping.AfterControlStatement &&
+          !I[1]->First->is(tok::r_brace))
         return 0;
       if (!Style.AllowShortLoopsOnASingleLine &&
-          Line.First->isOneOf(tok::kw_while, tok::kw_do, tok::kw_for))
+          Line.First->isOneOf(tok::kw_while, tok::kw_do, tok::kw_for) &&
+          Style.BraceWrapping.AfterControlStatement && I + 2 != E &&
+          !I[2]->First->is(tok::r_brace))
         return 0;
       // FIXME: Consider an option to allow short exception handling clauses on
       // a single line.
@@ -441,52 +505,78 @@ private:
         return 0;
     }
 
-    FormatToken *Tok = I[1]->First;
-    if (Tok->is(tok::r_brace) && !Tok->MustBreakBefore &&
-        (Tok->getNextNonComment() == nullptr ||
-         Tok->getNextNonComment()->is(tok::semi))) {
-      // We merge empty blocks even if the line exceeds the column limit.
-      Tok->SpacesRequiredBefore = 0;
-      Tok->CanBreakBefore = true;
-      return 1;
-    } else if (Limit != 0 && !Line.startsWith(tok::kw_namespace) &&
-               !startsExternCBlock(Line)) {
-      // We don't merge short records.
-      FormatToken *RecordTok =
-          Line.First->is(tok::kw_typedef) ? Line.First->Next : Line.First;
-      if (RecordTok &&
-          RecordTok->isOneOf(tok::kw_class, tok::kw_union, tok::kw_struct,
-                             Keywords.kw_interface))
-        return 0;
+    if (Line.Last->is(tok::l_brace)) {
+      FormatToken *Tok = I[1]->First;
+      if (Tok->is(tok::r_brace) && !Tok->MustBreakBefore &&
+          (Tok->getNextNonComment() == nullptr ||
+           Tok->getNextNonComment()->is(tok::semi))) {
+        // We merge empty blocks even if the line exceeds the column limit.
+        Tok->SpacesRequiredBefore = 0;
+        Tok->CanBreakBefore = true;
+        return 1;
+      } else if (Limit != 0 && !Line.startsWith(tok::kw_namespace) &&
+                 !startsExternCBlock(Line)) {
+        // We don't merge short records.
+        FormatToken *RecordTok = Line.First;
+        // Skip record modifiers.
+        while (RecordTok->Next &&
+               RecordTok->isOneOf(tok::kw_typedef, tok::kw_export,
+                                  Keywords.kw_declare, Keywords.kw_abstract,
+                                  tok::kw_default))
+          RecordTok = RecordTok->Next;
+        if (RecordTok &&
+            RecordTok->isOneOf(tok::kw_class, tok::kw_union, tok::kw_struct,
+                               Keywords.kw_interface))
+          return 0;
 
-      // Check that we still have three lines and they fit into the limit.
-      if (I + 2 == E || I[2]->Type == LT_Invalid)
-        return 0;
-      Limit = limitConsideringMacros(I + 2, E, Limit);
+        // Check that we still have three lines and they fit into the limit.
+        if (I + 2 == E || I[2]->Type == LT_Invalid)
+          return 0;
+        Limit = limitConsideringMacros(I + 2, E, Limit);
 
-      if (!nextTwoLinesFitInto(I, Limit))
-        return 0;
+        if (!nextTwoLinesFitInto(I, Limit))
+          return 0;
 
-      // Second, check that the next line does not contain any braces - if it
-      // does, readability declines when putting it into a single line.
-      if (I[1]->Last->is(TT_LineComment))
-        return 0;
-      do {
-        if (Tok->is(tok::l_brace) && Tok->BlockKind != BK_BracedInit)
+        // Second, check that the next line does not contain any braces - if it
+        // does, readability declines when putting it into a single line.
+        if (I[1]->Last->is(TT_LineComment))
+          return 0;
+        do {
+          if (Tok->is(tok::l_brace) && Tok->BlockKind != BK_BracedInit)
+            return 0;
+          Tok = Tok->Next;
+        } while (Tok);
+
+        // Last, check that the third line starts with a closing brace.
+        Tok = I[2]->First;
+        if (Tok->isNot(tok::r_brace))
           return 0;
-        Tok = Tok->Next;
-      } while (Tok);
 
-      // Last, check that the third line starts with a closing brace.
-      Tok = I[2]->First;
-      if (Tok->isNot(tok::r_brace))
-        return 0;
+        // Don't merge "if (a) { .. } else {".
+        if (Tok->Next && Tok->Next->is(tok::kw_else))
+          return 0;
 
-      // Don't merge "if (a) { .. } else {".
-      if (Tok->Next && Tok->Next->is(tok::kw_else))
+        return 2;
+      }
+    } else if (I[1]->First->is(tok::l_brace)) {
+      if (I[1]->Last->is(TT_LineComment))
         return 0;
 
-      return 2;
+      // Check for Limit <= 2 to account for the " {".
+      if (Limit <= 2 || (Style.ColumnLimit == 0 && containsMustBreak(*I)))
+        return 0;
+      Limit -= 2;
+      unsigned MergedLines = 0;
+      if (Style.AllowShortBlocksOnASingleLine ||
+          (I[1]->First == I[1]->Last && I + 2 != E &&
+           I[2]->First->is(tok::r_brace))) {
+        MergedLines = tryMergeSimpleBlock(I + 1, E, Limit);
+        // If we managed to merge the block, count the statement header, which
+        // is on a separate line.
+        if (MergedLines > 0)
+          ++MergedLines;
+      }
+      return MergedLines;
     }
     return 0;
   }
@@ -574,7 +664,9 @@ public:
   /// \brief Formats an \c AnnotatedLine and returns the penalty.
   ///
   /// If \p DryRun is \c false, directly applies the changes.
-  virtual unsigned formatLine(const AnnotatedLine &Line, unsigned FirstIndent,
+  virtual unsigned formatLine(const AnnotatedLine &Line,
+                              unsigned FirstIndent,
+                              unsigned FirstStartColumn,
                               bool DryRun) = 0;
 
 protected:
@@ -645,7 +737,8 @@ protected:
           *Child->First, /*Newlines=*/0, /*Spaces=*/1,
           /*StartOfTokenColumn=*/State.Column, State.Line->InPPDirective);
     }
-    Penalty += formatLine(*Child, State.Column + 1, DryRun);
+    Penalty +=
+        formatLine(*Child, State.Column + 1, /*FirstStartColumn=*/0, DryRun);
 
     State.Column += 1 + Child->Last->TotalLength;
     return true;
@@ -671,10 +764,10 @@ public:
   /// \brief Formats the line, simply keeping all of the input's line breaking
   /// decisions.
   unsigned formatLine(const AnnotatedLine &Line, unsigned FirstIndent,
-                      bool DryRun) override {
+                      unsigned FirstStartColumn, bool DryRun) override {
     assert(!DryRun);
-    LineState State =
-        Indenter->getInitialState(FirstIndent, &Line, /*DryRun=*/false);
+    LineState State = Indenter->getInitialState(FirstIndent, FirstStartColumn,
+                                                &Line, /*DryRun=*/false);
     while (State.NextToken) {
       bool Newline =
           Indenter->mustBreak(State) ||
@@ -697,9 +790,10 @@ public:
 
   /// \brief Puts all tokens into a single line.
   unsigned formatLine(const AnnotatedLine &Line, unsigned FirstIndent,
-                      bool DryRun) override {
+                      unsigned FirstStartColumn, bool DryRun) override {
     unsigned Penalty = 0;
-    LineState State = Indenter->getInitialState(FirstIndent, &Line, DryRun);
+    LineState State =
+        Indenter->getInitialState(FirstIndent, FirstStartColumn, &Line, DryRun);
     while (State.NextToken) {
       formatChildren(State, /*Newline=*/false, DryRun, Penalty);
       Indenter->addTokenToState(
@@ -721,8 +815,9 @@ public:
   /// \brief Formats the line by finding the best line breaks with line lengths
   /// below the column limit.
   unsigned formatLine(const AnnotatedLine &Line, unsigned FirstIndent,
-                      bool DryRun) override {
-    LineState State = Indenter->getInitialState(FirstIndent, &Line, DryRun);
+                      unsigned FirstStartColumn, bool DryRun) override {
+    LineState State =
+        Indenter->getInitialState(FirstIndent, FirstStartColumn, &Line, DryRun);
 
     // If the ObjC method declaration does not fit on a line, we should format
     // it with one arg per line.
@@ -763,7 +858,8 @@ private:
 
   /// \brief The BFS queue type.
   typedef std::priority_queue<QueueItem, std::vector<QueueItem>,
-                              std::greater<QueueItem>> QueueType;
+                              std::greater<QueueItem>>
+      QueueType;
 
   /// \brief Analyze the entire solution space starting from \p InitialState.
   ///
@@ -888,7 +984,10 @@ private:
 unsigned
 UnwrappedLineFormatter::format(const SmallVectorImpl<AnnotatedLine *> &Lines,
                                bool DryRun, int AdditionalIndent,
-                               bool FixBadIndentation) {
+                               bool FixBadIndentation,
+                               unsigned FirstStartColumn,
+                               unsigned NextStartColumn,
+                               unsigned LastStartColumn) {
   LineJoiner Joiner(Style, Keywords, Lines);
 
   // Try to look up already computed penalty in DryRun-mode.
@@ -908,9 +1007,10 @@ UnwrappedLineFormatter::format(const SmallVectorImpl<AnnotatedLine *> &Lines,
   // The minimum level of consecutive lines that have been formatted.
   unsigned RangeMinLevel = UINT_MAX;
 
+  bool FirstLine = true;
   for (const AnnotatedLine *Line =
            Joiner.getNextMergedLine(DryRun, IndentTracker);
-       Line; Line = NextLine) {
+       Line; Line = NextLine, FirstLine = false) {
     const AnnotatedLine &TheLine = *Line;
     unsigned Indent = IndentTracker.getIndent();
 
@@ -934,8 +1034,12 @@ UnwrappedLineFormatter::format(const SmallVectorImpl<AnnotatedLine *> &Lines,
     }
 
     if (ShouldFormat && TheLine.Type != LT_Invalid) {
-      if (!DryRun)
-        formatFirstToken(TheLine, PreviousLine, Indent);
+      if (!DryRun) {
+        bool LastLine = Line->First->is(tok::eof);
+        formatFirstToken(TheLine, PreviousLine,
+                         Indent,
+                         LastLine ? LastStartColumn : NextStartColumn + Indent);
+      }
 
       NextLine = Joiner.getNextMergedLine(DryRun, IndentTracker);
       unsigned ColumnLimit = getColumnLimit(TheLine.InPPDirective, NextLine);
@@ -944,16 +1048,18 @@ UnwrappedLineFormatter::format(const SmallVectorImpl<AnnotatedLine *> &Lines,
           (TheLine.Type == LT_ImportStatement &&
            (Style.Language != FormatStyle::LK_JavaScript ||
             !Style.JavaScriptWrapImports));
-
       if (Style.ColumnLimit == 0)
         NoColumnLimitLineFormatter(Indenter, Whitespaces, Style, this)
-            .formatLine(TheLine, Indent, DryRun);
+            .formatLine(TheLine, NextStartColumn + Indent,
+                        FirstLine ? FirstStartColumn : 0, DryRun);
       else if (FitsIntoOneLine)
         Penalty += NoLineBreakFormatter(Indenter, Whitespaces, Style, this)
-                       .formatLine(TheLine, Indent, DryRun);
+                       .formatLine(TheLine, NextStartColumn + Indent,
+                                   FirstLine ? FirstStartColumn : 0, DryRun);
       else
         Penalty += OptimizingLineFormatter(Indenter, Whitespaces, Style, this)
-                       .formatLine(TheLine, Indent, DryRun);
+                       .formatLine(TheLine, NextStartColumn + Indent,
+                                   FirstLine ? FirstStartColumn : 0, DryRun);
       RangeMinLevel = std::min(RangeMinLevel, TheLine.Level);
     } else {
       // If no token in the current line is affected, we still need to format
@@ -976,6 +1082,7 @@ UnwrappedLineFormatter::format(const SmallVectorImpl<AnnotatedLine *> &Lines,
         // Format the first token.
         if (ReformatLeadingWhitespace)
           formatFirstToken(TheLine, PreviousLine,
+                           TheLine.First->OriginalColumn,
                            TheLine.First->OriginalColumn);
         else
           Whitespaces->addUntouchableToken(*TheLine.First,
@@ -998,12 +1105,14 @@ UnwrappedLineFormatter::format(const SmallVectorImpl<AnnotatedLine *> &Lines,
 
 void UnwrappedLineFormatter::formatFirstToken(const AnnotatedLine &Line,
                                               const AnnotatedLine *PreviousLine,
-                                              unsigned Indent) {
-  FormatToken& RootToken = *Line.First;
+                                              unsigned Indent,
+                                              unsigned NewlineIndent) {
+  FormatToken &RootToken = *Line.First;
   if (RootToken.is(tok::eof)) {
     unsigned Newlines = std::min(RootToken.NewlinesBefore, 1u);
-    Whitespaces->replaceWhitespace(RootToken, Newlines, /*Spaces=*/0,
-                                   /*StartOfTokenColumn=*/0);
+    unsigned TokenIndent = Newlines ? NewlineIndent : 0;
+    Whitespaces->replaceWhitespace(RootToken, Newlines, TokenIndent,
+                                   TokenIndent);
     return;
   }
   unsigned Newlines =
@@ -1013,6 +1122,9 @@ void UnwrappedLineFormatter::formatFirstToken(const AnnotatedLine &Line,
       (!RootToken.Next ||
        (RootToken.Next->is(tok::semi) && !RootToken.Next->Next)))
     Newlines = std::min(Newlines, 1u);
+  // Remove empty lines at the start of nested blocks (lambdas/arrow functions)
+  if (PreviousLine == nullptr && Line.Level > 0)
+    Newlines = std::min(Newlines, 1u);
   if (Newlines == 0 && !RootToken.IsFirst)
     Newlines = 1;
   if (RootToken.IsFirst && !RootToken.HasUnescapedNewline)
@@ -1035,6 +1147,13 @@ void UnwrappedLineFormatter::formatFirstToken(const AnnotatedLine &Line,
       (!PreviousLine->InPPDirective || !RootToken.HasUnescapedNewline))
     Newlines = std::min(1u, Newlines);
 
+  if (Newlines)
+    Indent = NewlineIndent;
+
+  // Preprocessor directives get indented after the hash, if indented.
+  if (Line.Type == LT_PreprocessorDirective || Line.Type == LT_ImportStatement)
+    Indent = 0;
+
   Whitespaces->replaceWhitespace(RootToken, Newlines, Indent, Indent,
                                  Line.InPPDirective &&
                                      !RootToken.HasUnescapedNewline);
diff --git a/lib/Format/UnwrappedLineFormatter.h b/lib/Format/UnwrappedLineFormatter.h
index 55f0d1cac689..6432ca83a4c9 100644
--- a/lib/Format/UnwrappedLineFormatter.h
+++ b/lib/Format/UnwrappedLineFormatter.h
@@ -35,19 +35,22 @@ public:
                          const SourceManager &SourceMgr,
                          FormattingAttemptStatus *Status)
       : Indenter(Indenter), Whitespaces(Whitespaces), Style(Style),
-        Keywords(Keywords), SourceMgr(SourceMgr),
-        Status(Status) {}
+        Keywords(Keywords), SourceMgr(SourceMgr), Status(Status) {}
 
   /// \brief Format the current block and return the penalty.
   unsigned format(const SmallVectorImpl<AnnotatedLine *> &Lines,
                   bool DryRun = false, int AdditionalIndent = 0,
-                  bool FixBadIndentation = false);
+                  bool FixBadIndentation = false,
+                  unsigned FirstStartColumn = 0,
+                  unsigned NextStartColumn = 0,
+                  unsigned LastStartColumn = 0);
 
 private:
   /// \brief Add a new line and the required indent before the first Token
   /// of the \c UnwrappedLine if there was no structural parsing error.
   void formatFirstToken(const AnnotatedLine &Line,
-                        const AnnotatedLine *PreviousLine, unsigned Indent);
+                        const AnnotatedLine *PreviousLine, unsigned Indent,
+                        unsigned NewlineIndent);
 
   /// \brief Returns the column limit for a line, taking into account whether we
   /// need an escaped newline due to a continued preprocessor directive.
diff --git a/lib/Format/UnwrappedLineParser.cpp b/lib/Format/UnwrappedLineParser.cpp
index faac5a371c26..b8608dcac9c7 100644
--- a/lib/Format/UnwrappedLineParser.cpp
+++ b/lib/Format/UnwrappedLineParser.cpp
@@ -18,6 +18,8 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 
+#include <algorithm>
+
 #define DEBUG_TYPE "format-parser"
 
 namespace clang {
@@ -56,8 +58,7 @@ private:
 };
 
 static bool isLineComment(const FormatToken &FormatTok) {
-  return FormatTok.is(tok::comment) &&
-         FormatTok.TokenText.startswith("//");
+  return FormatTok.is(tok::comment) && !FormatTok.TokenText.startswith("/*");
 }
 
 // Checks if \p FormatTok is a line comment that continues the line comment
@@ -226,15 +227,21 @@ private:
 
 UnwrappedLineParser::UnwrappedLineParser(const FormatStyle &Style,
                                          const AdditionalKeywords &Keywords,
+                                         unsigned FirstStartColumn,
                                          ArrayRef<FormatToken *> Tokens,
                                          UnwrappedLineConsumer &Callback)
     : Line(new UnwrappedLine), MustBreakBeforeNextToken(false),
       CurrentLines(&Lines), Style(Style), Keywords(Keywords),
       CommentPragmasRegex(Style.CommentPragmas), Tokens(nullptr),
-      Callback(Callback), AllTokens(Tokens), PPBranchLevel(-1) {}
+      Callback(Callback), AllTokens(Tokens), PPBranchLevel(-1),
+      IfNdefCondition(nullptr), FoundIncludeGuardStart(false),
+      IncludeGuardRejected(false), FirstStartColumn(FirstStartColumn) {}
 
 void UnwrappedLineParser::reset() {
   PPBranchLevel = -1;
+  IfNdefCondition = nullptr;
+  FoundIncludeGuardStart = false;
+  IncludeGuardRejected = false;
   Line.reset(new UnwrappedLine);
   CommentsBeforeNextToken.clear();
   FormatTok = nullptr;
@@ -243,10 +250,12 @@ void UnwrappedLineParser::reset() {
   CurrentLines = &Lines;
   DeclarationScopeStack.clear();
   PPStack.clear();
+  Line->FirstStartColumn = FirstStartColumn;
 }
 
 void UnwrappedLineParser::parse() {
   IndexedTokenSource TokenSource(AllTokens);
+  Line->FirstStartColumn = FirstStartColumn;
   do {
     DEBUG(llvm::dbgs() << "----\n");
     reset();
@@ -326,6 +335,12 @@ void UnwrappedLineParser::parseLevel(bool HasOpeningBrace) {
       break;
     case tok::kw_default:
     case tok::kw_case:
+      if (Style.Language == FormatStyle::LK_JavaScript &&
+          Line->MustBeDeclaration) {
+        // A 'case: string' style field declaration.
+        parseStructuralElement();
+        break;
+      }
       if (!SwitchLabelEncountered &&
           (Style.IndentCaseLabels || (Line->InPPDirective && Line->Level == 1)))
         ++Line->Level;
@@ -346,7 +361,7 @@ void UnwrappedLineParser::calculateBraceTypes(bool ExpectClassBody) {
   // definitions, too.
   unsigned StoredPosition = Tokens->getPosition();
   FormatToken *Tok = FormatTok;
-  const FormatToken *PrevTok = getPreviousToken();
+  const FormatToken *PrevTok = Tok->Previous;
   // Keep a stack of positions of lbrace tokens. We will
   // update information about whether an lbrace starts a
   // braced init list or a different block during the loop.
@@ -364,13 +379,16 @@ void UnwrappedLineParser::calculateBraceTypes(bool ExpectClassBody) {
     switch (Tok->Tok.getKind()) {
     case tok::l_brace:
       if (Style.Language == FormatStyle::LK_JavaScript && PrevTok) {
-        if (PrevTok->is(tok::colon))
-          // A colon indicates this code is in a type, or a braced list
-          // following a label in an object literal ({a: {b: 1}}). The code
-          // below could be confused by semicolons between the individual
-          // members in a type member list, which would normally trigger
-          // BK_Block. In both cases, this must be parsed as an inline braced
-          // init.
+        if (PrevTok->isOneOf(tok::colon, tok::less))
+          // A ':' indicates this code is in a type, or a braced list
+          // following a label in an object literal ({a: {b: 1}}).
+          // A '<' could be an object used in a comparison, but that is nonsense
+          // code (can never return true), so more likely it is a generic type
+          // argument (`X<{a: string; b: number}>`).
+          // The code below could be confused by semicolons between the
+          // individual members in a type member list, which would normally
+          // trigger BK_Block. In both cases, this must be parsed as an inline
+          // braced init.
           Tok->BlockKind = BK_BracedInit;
         else if (PrevTok->is(tok::r_paren))
           // `) { }` can only occur in function or method declarations in JS.
@@ -452,6 +470,21 @@ void UnwrappedLineParser::calculateBraceTypes(bool ExpectClassBody) {
   FormatTok = Tokens->setPosition(StoredPosition);
 }
 
+template <class T>
+static inline void hash_combine(std::size_t &seed, const T &v) {
+  std::hash<T> hasher;
+  seed ^= hasher(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+}
+
+size_t UnwrappedLineParser::computePPHash() const {
+  size_t h = 0;
+  for (const auto &i : PPStack) {
+    hash_combine(h, size_t(i.Kind));
+    hash_combine(h, i.Line);
+  }
+  return h;
+}
+
 void UnwrappedLineParser::parseBlock(bool MustBeDeclaration, bool AddLevel,
                                      bool MunchSemi) {
   assert(FormatTok->isOneOf(tok::l_brace, TT_MacroBlockBegin) &&
@@ -459,16 +492,21 @@ void UnwrappedLineParser::parseBlock(bool MustBeDeclaration, bool AddLevel,
   const bool MacroBlock = FormatTok->is(TT_MacroBlockBegin);
   FormatTok->BlockKind = BK_Block;
 
+  size_t PPStartHash = computePPHash();
+
   unsigned InitialLevel = Line->Level;
-  nextToken();
+  nextToken(/*LevelDifference=*/AddLevel ? 1 : 0);
 
   if (MacroBlock && FormatTok->is(tok::l_paren))
     parseParens();
 
+  size_t NbPreprocessorDirectives =
+      CurrentLines == &Lines ? PreprocessorDirectives.size() : 0;
   addUnwrappedLine();
-  size_t OpeningLineIndex = CurrentLines->empty()
-                                ? (UnwrappedLine::kInvalidIndex)
-                                : (CurrentLines->size() - 1);
+  size_t OpeningLineIndex =
+      CurrentLines->empty()
+          ? (UnwrappedLine::kInvalidIndex)
+          : (CurrentLines->size() - 1 - NbPreprocessorDirectives);
 
   ScopedDeclarationState DeclarationState(*Line, DeclarationScopeStack,
                                           MustBeDeclaration);
@@ -486,7 +524,10 @@ void UnwrappedLineParser::parseBlock(bool MustBeDeclaration, bool AddLevel,
     return;
   }
 
-  nextToken(); // Munch the closing brace.
+  size_t PPEndHash = computePPHash();
+
+  // Munch the closing brace.
+  nextToken(/*LevelDifference=*/AddLevel ? -1 : 0);
 
   if (MacroBlock && FormatTok->is(tok::l_paren))
     parseParens();
@@ -494,11 +535,14 @@ void UnwrappedLineParser::parseBlock(bool MustBeDeclaration, bool AddLevel,
   if (MunchSemi && FormatTok->Tok.is(tok::semi))
     nextToken();
   Line->Level = InitialLevel;
-  Line->MatchingOpeningBlockLineIndex = OpeningLineIndex;
-  if (OpeningLineIndex != UnwrappedLine::kInvalidIndex) {
-    // Update the opening line to add the forward reference as well
-    (*CurrentLines)[OpeningLineIndex].MatchingOpeningBlockLineIndex =
-            CurrentLines->size() - 1;
+
+  if (PPStartHash == PPEndHash) {
+    Line->MatchingOpeningBlockLineIndex = OpeningLineIndex;
+    if (OpeningLineIndex != UnwrappedLine::kInvalidIndex) {
+      // Update the opening line to add the forward reference as well
+      (*CurrentLines)[OpeningLineIndex].MatchingOpeningBlockLineIndex =
+          CurrentLines->size() - 1;
+    }
   }
 }
 
@@ -555,9 +599,8 @@ void UnwrappedLineParser::parseChildBlock() {
   FormatTok->BlockKind = BK_Block;
   nextToken();
   {
-    bool SkipIndent =
-        (Style.Language == FormatStyle::LK_JavaScript &&
-         (isGoogScope(*Line) || isIIFE(*Line, Keywords)));
+    bool SkipIndent = (Style.Language == FormatStyle::LK_JavaScript &&
+                       (isGoogScope(*Line) || isIIFE(*Line, Keywords)));
     ScopedLineState LineState(*this);
     ScopedDeclarationState DeclarationState(*Line, DeclarationScopeStack,
                                             /*MustBeDeclaration=*/false);
@@ -606,10 +649,15 @@ void UnwrappedLineParser::parsePPDirective() {
 }
 
 void UnwrappedLineParser::conditionalCompilationCondition(bool Unreachable) {
-  if (Unreachable || (!PPStack.empty() && PPStack.back() == PP_Unreachable))
-    PPStack.push_back(PP_Unreachable);
+  size_t Line = CurrentLines->size();
+  if (CurrentLines == &PreprocessorDirectives)
+    Line += Lines.size();
+
+  if (Unreachable ||
+      (!PPStack.empty() && PPStack.back().Kind == PP_Unreachable))
+    PPStack.push_back({PP_Unreachable, Line});
   else
-    PPStack.push_back(PP_Conditional);
+    PPStack.push_back({PP_Conditional, Line});
 }
 
 void UnwrappedLineParser::conditionalCompilationStart(bool Unreachable) {
@@ -643,7 +691,7 @@ void UnwrappedLineParser::conditionalCompilationEnd() {
     }
   }
   // Guard against #endif's without #if.
-  if (PPBranchLevel > 0)
+  if (PPBranchLevel > -1)
     --PPBranchLevel;
   if (!PPChainBranchIndex.empty())
     PPChainBranchIndex.pop();
@@ -660,12 +708,35 @@ void UnwrappedLineParser::parsePPIf(bool IfDef) {
   if (IfDef && !IfNDef && FormatTok->TokenText == "SWIG")
     Unreachable = true;
   conditionalCompilationStart(Unreachable);
+  FormatToken *IfCondition = FormatTok;
+  // If there's a #ifndef on the first line, and the only lines before it are
+  // comments, it could be an include guard.
+  bool MaybeIncludeGuard = IfNDef;
+  if (!IncludeGuardRejected && !FoundIncludeGuardStart && MaybeIncludeGuard) {
+    for (auto &Line : Lines) {
+      if (!Line.Tokens.front().Tok->is(tok::comment)) {
+        MaybeIncludeGuard = false;
+        IncludeGuardRejected = true;
+        break;
+      }
+    }
+  }
+  --PPBranchLevel;
   parsePPUnknown();
+  ++PPBranchLevel;
+  if (!IncludeGuardRejected && !FoundIncludeGuardStart && MaybeIncludeGuard)
+    IfNdefCondition = IfCondition;
 }
 
 void UnwrappedLineParser::parsePPElse() {
+  // If a potential include guard has an #else, it's not an include guard.
+  if (FoundIncludeGuardStart && PPBranchLevel == 0)
+    FoundIncludeGuardStart = false;
   conditionalCompilationAlternative();
+  if (PPBranchLevel > -1)
+    --PPBranchLevel;
   parsePPUnknown();
+  ++PPBranchLevel;
 }
 
 void UnwrappedLineParser::parsePPElIf() { parsePPElse(); }
@@ -673,6 +744,16 @@ void UnwrappedLineParser::parsePPElIf() { parsePPElse(); }
 void UnwrappedLineParser::parsePPEndIf() {
   conditionalCompilationEnd();
   parsePPUnknown();
+  // If the #endif of a potential include guard is the last thing in the file,
+  // then we count it as a real include guard and subtract one from every
+  // preprocessor indent.
+  unsigned TokenPosition = Tokens->getPosition();
+  FormatToken *PeekNext = AllTokens[TokenPosition];
+  if (FoundIncludeGuardStart && PPBranchLevel == -1 && PeekNext->is(tok::eof) &&
+      Style.IndentPPDirectives != FormatStyle::PPDIS_None)
+    for (auto &Line : Lines)
+      if (Line.InPPDirective && Line.Level > 0)
+        --Line.Level;
 }
 
 void UnwrappedLineParser::parsePPDefine() {
@@ -682,14 +763,26 @@ void UnwrappedLineParser::parsePPDefine() {
     parsePPUnknown();
     return;
   }
+  if (IfNdefCondition && IfNdefCondition->TokenText == FormatTok->TokenText) {
+    FoundIncludeGuardStart = true;
+    for (auto &Line : Lines) {
+      if (!Line.Tokens.front().Tok->isOneOf(tok::comment, tok::hash)) {
+        FoundIncludeGuardStart = false;
+        break;
+      }
+    }
+  }
+  IfNdefCondition = nullptr;
   nextToken();
   if (FormatTok->Tok.getKind() == tok::l_paren &&
       FormatTok->WhitespaceRange.getBegin() ==
           FormatTok->WhitespaceRange.getEnd()) {
     parseParens();
   }
+  if (Style.IndentPPDirectives == FormatStyle::PPDIS_AfterHash)
+    Line->Level += PPBranchLevel + 1;
   addUnwrappedLine();
-  Line->Level = 1;
+  ++Line->Level;
 
   // Errors during a preprocessor directive can only affect the layout of the
   // preprocessor directive, and thus we ignore them. An alternative approach
@@ -703,7 +796,10 @@ void UnwrappedLineParser::parsePPUnknown() {
   do {
     nextToken();
   } while (!eof());
+  if (Style.IndentPPDirectives == FormatStyle::PPDIS_AfterHash)
+    Line->Level += PPBranchLevel + 1;
   addUnwrappedLine();
+  IfNdefCondition = nullptr;
 }
 
 // Here we blacklist certain tokens that are not usually the first token in an
@@ -746,8 +842,8 @@ static bool mustBeJSIdent(const AdditionalKeywords &Keywords,
               Keywords.kw_function, Keywords.kw_import, Keywords.kw_is,
               Keywords.kw_let, Keywords.kw_var, tok::kw_const,
               Keywords.kw_abstract, Keywords.kw_extends, Keywords.kw_implements,
-              Keywords.kw_instanceof, Keywords.kw_interface,
-              Keywords.kw_throws, Keywords.kw_from));
+              Keywords.kw_instanceof, Keywords.kw_interface, Keywords.kw_throws,
+              Keywords.kw_from));
 }
 
 static bool mustBeJSIdentOrValue(const AdditionalKeywords &Keywords,
@@ -800,11 +896,14 @@ void UnwrappedLineParser::readTokenWithJavaScriptASI() {
   bool PreviousMustBeValue = mustBeJSIdentOrValue(Keywords, Previous);
   bool PreviousStartsTemplateExpr =
       Previous->is(TT_TemplateString) && Previous->TokenText.endswith("${");
-  if (PreviousMustBeValue && Line && Line->Tokens.size() > 1) {
-    // If the token before the previous one is an '@', the previous token is an
-    // annotation and can precede another identifier/value.
-    const FormatToken *PrePrevious = std::prev(Line->Tokens.end(), 2)->Tok;
-    if (PrePrevious->is(tok::at))
+  if (PreviousMustBeValue || Previous->is(tok::r_paren)) {
+    // If the line contains an '@' sign, the previous token might be an
+    // annotation, which can precede another identifier/value.
+    bool HasAt = std::find_if(Line->Tokens.begin(), Line->Tokens.end(),
+                              [](UnwrappedLineNode &LineNode) {
+                                return LineNode.Tok->is(tok::at);
+                              }) != Line->Tokens.end();
+    if (HasAt)
       return;
   }
   if (Next->is(tok::exclaim) && PreviousMustBeValue)
@@ -817,7 +916,8 @@ void UnwrappedLineParser::readTokenWithJavaScriptASI() {
        Previous->isOneOf(tok::r_square, tok::r_paren, tok::plusplus,
                          tok::minusminus)))
     return addUnwrappedLine();
-  if (PreviousMustBeValue && isJSDeclOrStmt(Keywords, Next))
+  if ((PreviousMustBeValue || Previous->is(tok::r_paren)) &&
+      isJSDeclOrStmt(Keywords, Next))
     return addUnwrappedLine();
 }
 
@@ -922,13 +1022,22 @@ void UnwrappedLineParser::parseStructuralElement() {
     parseDoWhile();
     return;
   case tok::kw_switch:
+    if (Style.Language == FormatStyle::LK_JavaScript && Line->MustBeDeclaration)
+      // 'switch: string' field declaration.
+      break;
     parseSwitch();
     return;
   case tok::kw_default:
+    if (Style.Language == FormatStyle::LK_JavaScript && Line->MustBeDeclaration)
+      // 'default: string' field declaration.
+      break;
     nextToken();
     parseLabel();
     return;
   case tok::kw_case:
+    if (Style.Language == FormatStyle::LK_JavaScript && Line->MustBeDeclaration)
+      // 'case: string' field declaration.
+      break;
     parseCaseLabel();
     return;
   case tok::kw_try:
@@ -940,7 +1049,12 @@ void UnwrappedLineParser::parseStructuralElement() {
     if (FormatTok->Tok.is(tok::string_literal)) {
       nextToken();
       if (FormatTok->Tok.is(tok::l_brace)) {
-        parseBlock(/*MustBeDeclaration=*/true, /*AddLevel=*/false);
+        if (Style.BraceWrapping.AfterExternBlock) {
+          addUnwrappedLine();
+          parseBlock(/*MustBeDeclaration=*/true);
+        } else {
+          parseBlock(/*MustBeDeclaration=*/true, /*AddLevel=*/false);
+        }
         addUnwrappedLine();
         return;
       }
@@ -996,7 +1110,7 @@ void UnwrappedLineParser::parseStructuralElement() {
     break;
   }
   do {
-    const FormatToken *Previous = getPreviousToken();
+    const FormatToken *Previous = FormatTok->Previous;
     switch (FormatTok->Tok.getKind()) {
     case tok::at:
       nextToken();
@@ -1186,7 +1300,7 @@ void UnwrappedLineParser::parseStructuralElement() {
         nextToken();
         parseBracedList();
       } else if (Style.Language == FormatStyle::LK_Proto &&
-               FormatTok->Tok.is(tok::less)) {
+                 FormatTok->Tok.is(tok::less)) {
         nextToken();
         parseBracedList(/*ContinueOnSemicolons=*/false,
                         /*ClosingBraceKind=*/tok::greater);
@@ -1210,14 +1324,6 @@ bool UnwrappedLineParser::tryToParseLambda() {
     nextToken();
     return false;
   }
-  const FormatToken* Previous = getPreviousToken();
-  if (Previous &&
-      (Previous->isOneOf(tok::identifier, tok::kw_operator, tok::kw_new,
-                         tok::kw_delete) ||
-       Previous->closesScope() || Previous->isSimpleTypeSpecifier())) {
-    nextToken();
-    return false;
-  }
   assert(FormatTok->is(tok::l_square));
   FormatToken &LSquare = *FormatTok;
   if (!tryToParseLambdaIntroducer())
@@ -1260,49 +1366,18 @@ bool UnwrappedLineParser::tryToParseLambda() {
 }
 
 bool UnwrappedLineParser::tryToParseLambdaIntroducer() {
-  nextToken();
-  if (FormatTok->is(tok::equal)) {
-    nextToken();
-    if (FormatTok->is(tok::r_square)) {
-      nextToken();
-      return true;
-    }
-    if (FormatTok->isNot(tok::comma))
-      return false;
-    nextToken();
-  } else if (FormatTok->is(tok::amp)) {
-    nextToken();
-    if (FormatTok->is(tok::r_square)) {
-      nextToken();
-      return true;
-    }
-    if (!FormatTok->isOneOf(tok::comma, tok::identifier)) {
-      return false;
-    }
-    if (FormatTok->is(tok::comma))
-      nextToken();
-  } else if (FormatTok->is(tok::r_square)) {
+  const FormatToken *Previous = FormatTok->Previous;
+  if (Previous &&
+      (Previous->isOneOf(tok::identifier, tok::kw_operator, tok::kw_new,
+                         tok::kw_delete) ||
+       FormatTok->isCppStructuredBinding(Style) || Previous->closesScope() ||
+       Previous->isSimpleTypeSpecifier())) {
     nextToken();
-    return true;
+    return false;
   }
-  do {
-    if (FormatTok->is(tok::amp))
-      nextToken();
-    if (!FormatTok->isOneOf(tok::identifier, tok::kw_this))
-      return false;
-    nextToken();
-    if (FormatTok->is(tok::ellipsis))
-      nextToken();
-    if (FormatTok->is(tok::comma)) {
-      nextToken();
-    } else if (FormatTok->is(tok::r_square)) {
-      nextToken();
-      return true;
-    } else {
-      return false;
-    }
-  } while (!eof());
-  return false;
+  nextToken();
+  parseSquare(/*LambdaIntroducer=*/true);
+  return true;
 }
 
 void UnwrappedLineParser::tryToParseJSFunction() {
@@ -1419,6 +1494,15 @@ bool UnwrappedLineParser::parseBracedList(bool ContinueOnSemicolons,
       nextToken();
       parseBracedList();
       break;
+    case tok::less:
+      if (Style.Language == FormatStyle::LK_Proto) {
+        nextToken();
+        parseBracedList(/*ContinueOnSemicolons=*/false,
+                        /*ClosingBraceKind=*/tok::greater);
+      } else {
+        nextToken();
+      }
+      break;
     case tok::semi:
       // JavaScript (or more precisely TypeScript) can have semicolons in braced
       // lists (in so-called TypeMemberLists). Thus, the semicolon cannot be
@@ -1495,10 +1579,12 @@ void UnwrappedLineParser::parseParens() {
   } while (!eof());
 }
 
-void UnwrappedLineParser::parseSquare() {
-  assert(FormatTok->Tok.is(tok::l_square) && "'[' expected.");
-  if (tryToParseLambda())
-    return;
+void UnwrappedLineParser::parseSquare(bool LambdaIntroducer) {
+  if (!LambdaIntroducer) {
+    assert(FormatTok->Tok.is(tok::l_square) && "'[' expected.");
+    if (tryToParseLambda())
+      return;
+  }
   do {
     switch (FormatTok->Tok.getKind()) {
     case tok::l_paren:
@@ -1939,6 +2025,17 @@ void UnwrappedLineParser::parseRecord(bool ParseAsExpr) {
          ((Style.Language == FormatStyle::LK_Java ||
            Style.Language == FormatStyle::LK_JavaScript) &&
           FormatTok->isOneOf(tok::period, tok::comma))) {
+    if (Style.Language == FormatStyle::LK_JavaScript &&
+        FormatTok->isOneOf(Keywords.kw_extends, Keywords.kw_implements)) {
+      // JavaScript/TypeScript supports inline object types in
+      // extends/implements positions:
+      //     class Foo implements {bar: number} { }
+      nextToken();
+      if (FormatTok->is(tok::l_brace)) {
+        tryToParseBracedList();
+        continue;
+      }
+    }
     bool IsNonMacroIdentifier =
         FormatTok->is(tok::identifier) &&
         FormatTok->TokenText != FormatTok->TokenText.upper();
@@ -2090,7 +2187,7 @@ void UnwrappedLineParser::parseJavaScriptEs6ImportExport() {
   while (!eof()) {
     if (FormatTok->is(tok::semi))
       return;
-    if (Line->Tokens.size() == 0) {
+    if (Line->Tokens.empty()) {
       // Common issue: Automatic Semicolon Insertion wrapped the line, so the
       // import statement should terminate.
       return;
@@ -2107,14 +2204,15 @@ void UnwrappedLineParser::parseJavaScriptEs6ImportExport() {
 
 LLVM_ATTRIBUTE_UNUSED static void printDebugInfo(const UnwrappedLine &Line,
                                                  StringRef Prefix = "") {
-  llvm::dbgs() << Prefix << "Line(" << Line.Level << ")"
+  llvm::dbgs() << Prefix << "Line(" << Line.Level
+               << ", FSC=" << Line.FirstStartColumn << ")"
                << (Line.InPPDirective ? " MACRO" : "") << ": ";
   for (std::list<UnwrappedLineNode>::const_iterator I = Line.Tokens.begin(),
                                                     E = Line.Tokens.end();
        I != E; ++I) {
     llvm::dbgs() << I->Tok->Tok.getName() << "["
-                 << "T=" << I->Tok->Type
-                 << ", OC=" << I->Tok->OriginalColumn << "] ";
+                 << "T=" << I->Tok->Type << ", OC=" << I->Tok->OriginalColumn
+                 << "] ";
   }
   for (std::list<UnwrappedLineNode>::const_iterator I = Line.Tokens.begin(),
                                                     E = Line.Tokens.end();
@@ -2140,12 +2238,15 @@ void UnwrappedLineParser::addUnwrappedLine() {
   CurrentLines->push_back(std::move(*Line));
   Line->Tokens.clear();
   Line->MatchingOpeningBlockLineIndex = UnwrappedLine::kInvalidIndex;
+  Line->FirstStartColumn = 0;
   if (CurrentLines == &Lines && !PreprocessorDirectives.empty()) {
     CurrentLines->append(
         std::make_move_iterator(PreprocessorDirectives.begin()),
         std::make_move_iterator(PreprocessorDirectives.end()));
     PreprocessorDirectives.clear();
   }
+  // Disconnect the current token from the last token on the previous line.
+  FormatTok->Previous = nullptr;
 }
 
 bool UnwrappedLineParser::eof() const { return FormatTok->Tok.is(tok::eof); }
@@ -2287,23 +2388,17 @@ void UnwrappedLineParser::flushComments(bool NewlineBeforeNext) {
   CommentsBeforeNextToken.clear();
 }
 
-void UnwrappedLineParser::nextToken() {
+void UnwrappedLineParser::nextToken(int LevelDifference) {
   if (eof())
     return;
   flushComments(isOnNewLine(*FormatTok));
   pushToken(FormatTok);
+  FormatToken *Previous = FormatTok;
   if (Style.Language != FormatStyle::LK_JavaScript)
-    readToken();
+    readToken(LevelDifference);
   else
     readTokenWithJavaScriptASI();
-}
-
-const FormatToken *UnwrappedLineParser::getPreviousToken() {
-  // FIXME: This is a dirty way to access the previous token. Find a better
-  // solution.
-  if (!Line || Line->Tokens.empty())
-    return nullptr;
-  return Line->Tokens.back().Tok;
+  FormatTok->Previous = Previous;
 }
 
 void UnwrappedLineParser::distributeComments(
@@ -2343,8 +2438,7 @@ void UnwrappedLineParser::distributeComments(
   }
   for (unsigned i = 0, e = Comments.size(); i < e; ++i) {
     FormatToken *FormatTok = Comments[i];
-    if (HasTrailAlignedWithNextToken &&
-        i == StartOfTrailAlignedWithNextToken) {
+    if (HasTrailAlignedWithNextToken && i == StartOfTrailAlignedWithNextToken) {
       FormatTok->ContinuesLineCommentSection = false;
     } else {
       FormatTok->ContinuesLineCommentSection =
@@ -2362,7 +2456,7 @@ void UnwrappedLineParser::distributeComments(
   }
 }
 
-void UnwrappedLineParser::readToken() {
+void UnwrappedLineParser::readToken(int LevelDifference) {
   SmallVector<FormatToken *, 1> Comments;
   do {
     FormatTok = Tokens->getNextToken();
@@ -2375,6 +2469,10 @@ void UnwrappedLineParser::readToken() {
       // directives only after that unwrapped line was finished later.
       bool SwitchToPreprocessorLines = !Line->Tokens.empty();
       ScopedLineState BlockState(*this, SwitchToPreprocessorLines);
+      assert((LevelDifference >= 0 ||
+              static_cast<unsigned>(-LevelDifference) <= Line->Level) &&
+             "LevelDifference makes Line->Level negative");
+      Line->Level += LevelDifference;
       // Comments stored before the preprocessor directive need to be output
       // before the preprocessor directive, at the same level as the
       // preprocessor directive, as we consider them to apply to the directive.
@@ -2395,7 +2493,7 @@ void UnwrappedLineParser::readToken() {
       FormatTok->MustBreakBefore = true;
     }
 
-    if (!PPStack.empty() && (PPStack.back() == PP_Unreachable) &&
+    if (!PPStack.empty() && (PPStack.back().Kind == PP_Unreachable) &&
         !Line->InPPDirective) {
       continue;
     }
diff --git a/lib/Format/UnwrappedLineParser.h b/lib/Format/UnwrappedLineParser.h
index a2aa2f006728..1d8ccabbd0f8 100644
--- a/lib/Format/UnwrappedLineParser.h
+++ b/lib/Format/UnwrappedLineParser.h
@@ -56,6 +56,8 @@ struct UnwrappedLine {
   size_t MatchingOpeningBlockLineIndex;
 
   static const size_t kInvalidIndex = -1;
+
+  unsigned FirstStartColumn = 0;
 };
 
 class UnwrappedLineConsumer {
@@ -71,6 +73,7 @@ class UnwrappedLineParser {
 public:
   UnwrappedLineParser(const FormatStyle &Style,
                       const AdditionalKeywords &Keywords,
+                      unsigned FirstStartColumn,
                       ArrayRef<FormatToken *> Tokens,
                       UnwrappedLineConsumer &Callback);
 
@@ -96,7 +99,7 @@ private:
   bool parseBracedList(bool ContinueOnSemicolons = false,
                        tok::TokenKind ClosingBraceKind = tok::r_brace);
   void parseParens();
-  void parseSquare();
+  void parseSquare(bool LambdaIntroducer = false);
   void parseIfThenElse();
   void parseTryCatch();
   void parseForOrWhileLoop();
@@ -123,9 +126,12 @@ private:
   void tryToParseJSFunction();
   void addUnwrappedLine();
   bool eof() const;
-  void nextToken();
-  const FormatToken *getPreviousToken();
-  void readToken();
+  // LevelDifference is the difference of levels after and before the current
+  // token. For example:
+  // - if the token is '{' and opens a block, LevelDifference is 1.
+  // - if the token is '}' and closes a block, LevelDifference is -1.
+  void nextToken(int LevelDifference = 0);
+  void readToken(int LevelDifference = 0);
 
   // Decides which comment tokens should be added to the current line and which
   // should be added as comments before the next token.
@@ -156,6 +162,11 @@ private:
 
   bool isOnNewLine(const FormatToken &FormatTok);
 
+  // Compute hash of the current preprocessor branch.
+  // This is used to identify the different branches, and thus track if block
+  // open and close in the same branch.
+  size_t computePPHash() const;
+
   // FIXME: We are constantly running into bugs where Line.Level is incorrectly
   // subtracted from beyond 0. Introduce a method to subtract from Line.Level
   // and use that everywhere in the Parser.
@@ -174,7 +185,7 @@ private:
 
   // Preprocessor directives are parsed out-of-order from other unwrapped lines.
   // Thus, we need to keep a list of preprocessor directives to be reported
-  // after an unwarpped line that has been started was finished.
+  // after an unwrapped line that has been started was finished.
   SmallVector<UnwrappedLine, 4> PreprocessorDirectives;
 
   // New unwrapped lines are added via CurrentLines.
@@ -207,8 +218,14 @@ private:
     PP_Unreachable  // #if 0 or a conditional preprocessor block inside #if 0
   };
 
+  struct PPBranch {
+    PPBranch(PPBranchKind Kind, size_t Line) : Kind(Kind), Line(Line) {}
+    PPBranchKind Kind;
+    size_t Line;
+  };
+
   // Keeps a stack of currently active preprocessor branching directives.
-  SmallVector<PPBranchKind, 16> PPStack;
+  SmallVector<PPBranch, 16> PPStack;
 
   // The \c UnwrappedLineParser re-parses the code for each combination
   // of preprocessor branches that can be taken.
@@ -231,6 +248,15 @@ private:
   // sequence.
   std::stack<int> PPChainBranchIndex;
 
+  // Contains the #ifndef condition for a potential include guard.
+  FormatToken *IfNdefCondition;
+  bool FoundIncludeGuardStart;
+  bool IncludeGuardRejected;
+  // Contains the first start column where the source begins. This is zero for
+  // normal source code and may be nonzero when formatting a code fragment that
+  // does not start at the beginning of the file.
+  unsigned FirstStartColumn;
+
   friend class ScopedLineState;
   friend class CompoundStatementIndenter;
 };
@@ -243,8 +269,9 @@ struct UnwrappedLineNode {
   SmallVector<UnwrappedLine, 0> Children;
 };
 
-inline UnwrappedLine::UnwrappedLine() : Level(0), InPPDirective(false),
-  MustBeDeclaration(false), MatchingOpeningBlockLineIndex(kInvalidIndex) {}
+inline UnwrappedLine::UnwrappedLine()
+    : Level(0), InPPDirective(false), MustBeDeclaration(false),
+      MatchingOpeningBlockLineIndex(kInvalidIndex) {}
 
 } // end namespace format
 } // end namespace clang
diff --git a/lib/Format/UsingDeclarationsSorter.cpp b/lib/Format/UsingDeclarationsSorter.cpp
index fb4f59fbc9bc..ef0c7a7d5a45 100644
--- a/lib/Format/UsingDeclarationsSorter.cpp
+++ b/lib/Format/UsingDeclarationsSorter.cpp
@@ -26,6 +26,45 @@ namespace format {
 
 namespace {
 
+// The order of using declaration is defined as follows:
+// Split the strings by "::" and discard any initial empty strings. The last
+// element of each list is a non-namespace name; all others are namespace
+// names. Sort the lists of names lexicographically, where the sort order of
+// individual names is that all non-namespace names come before all namespace
+// names, and within those groups, names are in case-insensitive lexicographic
+// order.
+int compareLabels(StringRef A, StringRef B) {
+  SmallVector<StringRef, 2> NamesA;
+  A.split(NamesA, "::", /*MaxSplit=*/-1, /*KeepEmpty=*/false);
+  SmallVector<StringRef, 2> NamesB;
+  B.split(NamesB, "::", /*MaxSplit=*/-1, /*KeepEmpty=*/false);
+  size_t SizeA = NamesA.size();
+  size_t SizeB = NamesB.size();
+  for (size_t I = 0, E = std::min(SizeA, SizeB); I < E; ++I) {
+    if (I + 1 == SizeA) {
+      // I is the last index of NamesA and NamesA[I] is a non-namespace name.
+
+      // Non-namespace names come before all namespace names.
+      if (SizeB > SizeA)
+        return -1;
+
+      // Two names within a group compare case-insensitively.
+      return NamesA[I].compare_lower(NamesB[I]);
+    }
+
+    // I is the last index of NamesB and NamesB[I] is a non-namespace name.
+    // Non-namespace names come before all namespace names.
+    if (I + 1 == SizeB)
+      return 1;
+
+    // Two namespaces names within a group compare case-insensitively.
+    int C = NamesA[I].compare_lower(NamesB[I]);
+    if (C != 0)
+      return C;
+  }
+  return 0;
+}
+
 struct UsingDeclaration {
   const AnnotatedLine *Line;
   std::string Label;
@@ -34,7 +73,7 @@ struct UsingDeclaration {
       : Line(Line), Label(Label) {}
 
   bool operator<(const UsingDeclaration &Other) const {
-    return Label < Other.Label;
+    return compareLabels(Label, Other.Label) < 0;
   }
 };
 
@@ -76,10 +115,42 @@ std::string computeUsingDeclarationLabel(const FormatToken *UsingTok) {
 void endUsingDeclarationBlock(
     SmallVectorImpl<UsingDeclaration> *UsingDeclarations,
     const SourceManager &SourceMgr, tooling::Replacements *Fixes) {
+  bool BlockAffected = false;
+  for (const UsingDeclaration &Declaration : *UsingDeclarations) {
+    if (Declaration.Line->Affected) {
+      BlockAffected = true;
+      break;
+    }
+  }
+  if (!BlockAffected) {
+    UsingDeclarations->clear();
+    return;
+  }
   SmallVector<UsingDeclaration, 4> SortedUsingDeclarations(
       UsingDeclarations->begin(), UsingDeclarations->end());
-  std::sort(SortedUsingDeclarations.begin(), SortedUsingDeclarations.end());
+  std::stable_sort(SortedUsingDeclarations.begin(),
+                   SortedUsingDeclarations.end());
+  SortedUsingDeclarations.erase(
+      std::unique(SortedUsingDeclarations.begin(),
+                  SortedUsingDeclarations.end(),
+                  [](const UsingDeclaration &a, const UsingDeclaration &b) {
+                    return a.Label == b.Label;
+                  }),
+      SortedUsingDeclarations.end());
   for (size_t I = 0, E = UsingDeclarations->size(); I < E; ++I) {
+    if (I >= SortedUsingDeclarations.size()) {
+      // This using declaration has been deduplicated, delete it.
+      auto Begin =
+          (*UsingDeclarations)[I].Line->First->WhitespaceRange.getBegin();
+      auto End = (*UsingDeclarations)[I].Line->Last->Tok.getEndLoc();
+      auto Range = CharSourceRange::getCharRange(Begin, End);
+      auto Err = Fixes->add(tooling::Replacement(SourceMgr, Range, ""));
+      if (Err) {
+        llvm::errs() << "Error while sorting using declarations: "
+                     << llvm::toString(std::move(Err)) << "\n";
+      }
+      continue;
+    }
     if ((*UsingDeclarations)[I].Line == SortedUsingDeclarations[I].Line)
       continue;
     auto Begin = (*UsingDeclarations)[I].Line->First->Tok.getLocation();
@@ -112,7 +183,7 @@ UsingDeclarationsSorter::UsingDeclarationsSorter(const Environment &Env,
                                                  const FormatStyle &Style)
     : TokenAnalyzer(Env, Style) {}
 
-tooling::Replacements UsingDeclarationsSorter::analyze(
+std::pair<tooling::Replacements, unsigned> UsingDeclarationsSorter::analyze(
     TokenAnnotator &Annotator, SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
     FormatTokenLexer &Tokens) {
   const SourceManager &SourceMgr = Env.getSourceManager();
@@ -121,15 +192,17 @@ tooling::Replacements UsingDeclarationsSorter::analyze(
   tooling::Replacements Fixes;
   SmallVector<UsingDeclaration, 4> UsingDeclarations;
   for (size_t I = 0, E = AnnotatedLines.size(); I != E; ++I) {
-    if (!AnnotatedLines[I]->Affected || AnnotatedLines[I]->InPPDirective ||
-        !AnnotatedLines[I]->startsWith(tok::kw_using) ||
-        AnnotatedLines[I]->First->Finalized) {
+    const auto *FirstTok = AnnotatedLines[I]->First;
+    if (AnnotatedLines[I]->InPPDirective ||
+        !AnnotatedLines[I]->startsWith(tok::kw_using) || FirstTok->Finalized) {
       endUsingDeclarationBlock(&UsingDeclarations, SourceMgr, &Fixes);
       continue;
     }
-    if (AnnotatedLines[I]->First->NewlinesBefore > 1)
+    if (FirstTok->NewlinesBefore > 1)
       endUsingDeclarationBlock(&UsingDeclarations, SourceMgr, &Fixes);
-    std::string Label = computeUsingDeclarationLabel(AnnotatedLines[I]->First);
+    const auto *UsingTok =
+        FirstTok->is(tok::comment) ? FirstTok->getNextNonComment() : FirstTok;
+    std::string Label = computeUsingDeclarationLabel(UsingTok);
     if (Label.empty()) {
       endUsingDeclarationBlock(&UsingDeclarations, SourceMgr, &Fixes);
       continue;
@@ -137,7 +210,7 @@ tooling::Replacements UsingDeclarationsSorter::analyze(
     UsingDeclarations.push_back(UsingDeclaration(AnnotatedLines[I], Label));
   }
   endUsingDeclarationBlock(&UsingDeclarations, SourceMgr, &Fixes);
-  return Fixes;
+  return {Fixes, 0};
 }
 
 } // namespace format
diff --git a/lib/Format/UsingDeclarationsSorter.h b/lib/Format/UsingDeclarationsSorter.h
index f7d5f97e3a2a..6f137712d841 100644
--- a/lib/Format/UsingDeclarationsSorter.h
+++ b/lib/Format/UsingDeclarationsSorter.h
@@ -25,7 +25,7 @@ class UsingDeclarationsSorter : public TokenAnalyzer {
 public:
   UsingDeclarationsSorter(const Environment &Env, const FormatStyle &Style);
 
-  tooling::Replacements
+  std::pair<tooling::Replacements, unsigned>
   analyze(TokenAnnotator &Annotator,
           SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
           FormatTokenLexer &Tokens) override;
diff --git a/lib/Format/WhitespaceManager.cpp b/lib/Format/WhitespaceManager.cpp
index 377ec3a681b6..a5477a996327 100644
--- a/lib/Format/WhitespaceManager.cpp
+++ b/lib/Format/WhitespaceManager.cpp
@@ -67,6 +67,11 @@ void WhitespaceManager::addUntouchableToken(const FormatToken &Tok,
                            /*IsInsideToken=*/false));
 }
 
+llvm::Error
+WhitespaceManager::addReplacement(const tooling::Replacement &Replacement) {
+  return Replaces.add(Replacement);
+}
+
 void WhitespaceManager::replaceWhitespaceInToken(
     const FormatToken &Tok, unsigned Offset, unsigned ReplaceChars,
     StringRef PreviousPostfix, StringRef CurrentPrefix, bool InPPDirective,
@@ -166,15 +171,15 @@ void WhitespaceManager::calculateLineBreakInformation() {
         // BreakableLineCommentSection does comment reflow changes and here is
         // the aligning of trailing comments. Consider the case where we reflow
         // the second line up in this example:
-        // 
+        //
         // // line 1
         // // line 2
-        // 
+        //
         // That amounts to 2 changes by BreakableLineCommentSection:
         //  - the first, delimited by (), for the whitespace between the tokens,
         //  - and second, delimited by [], for the whitespace at the beginning
         //  of the second token:
-        // 
+        //
         // // line 1(
         // )[// ]line 2
         //
@@ -608,8 +613,9 @@ void WhitespaceManager::generateChanges() {
     if (C.CreateReplacement) {
       std::string ReplacementText = C.PreviousLinePostfix;
       if (C.ContinuesPPDirective)
-        appendNewlineText(ReplacementText, C.NewlinesBefore,
-                          C.PreviousEndOfTokenColumn, C.EscapedNewlineColumn);
+        appendEscapedNewlineText(ReplacementText, C.NewlinesBefore,
+                                 C.PreviousEndOfTokenColumn,
+                                 C.EscapedNewlineColumn);
       else
         appendNewlineText(ReplacementText, C.NewlinesBefore);
       appendIndentText(ReplacementText, C.Tok->IndentLevel,
@@ -621,8 +627,7 @@ void WhitespaceManager::generateChanges() {
   }
 }
 
-void WhitespaceManager::storeReplacement(SourceRange Range,
-                                         StringRef Text) {
+void WhitespaceManager::storeReplacement(SourceRange Range, StringRef Text) {
   unsigned WhitespaceLength = SourceMgr.getFileOffset(Range.getEnd()) -
                               SourceMgr.getFileOffset(Range.getBegin());
   // Don't create a replacement, if it does not change anything.
@@ -645,16 +650,16 @@ void WhitespaceManager::appendNewlineText(std::string &Text,
     Text.append(UseCRLF ? "\r\n" : "\n");
 }
 
-void WhitespaceManager::appendNewlineText(std::string &Text, unsigned Newlines,
-                                          unsigned PreviousEndOfTokenColumn,
-                                          unsigned EscapedNewlineColumn) {
+void WhitespaceManager::appendEscapedNewlineText(
+    std::string &Text, unsigned Newlines, unsigned PreviousEndOfTokenColumn,
+    unsigned EscapedNewlineColumn) {
   if (Newlines > 0) {
-    unsigned Offset =
-        std::min<int>(EscapedNewlineColumn - 2, PreviousEndOfTokenColumn);
+    unsigned Spaces =
+        std::max<int>(1, EscapedNewlineColumn - PreviousEndOfTokenColumn - 1);
     for (unsigned i = 0; i < Newlines; ++i) {
-      Text.append(EscapedNewlineColumn - Offset - 1, ' ');
+      Text.append(Spaces, ' ');
       Text.append(UseCRLF ? "\\\r\n" : "\\\n");
-      Offset = 0;
+      Spaces = std::max<int>(0, EscapedNewlineColumn - 1);
     }
   }
 }
diff --git a/lib/Format/WhitespaceManager.h b/lib/Format/WhitespaceManager.h
index 4e78ab43abaf..af20dc5616a7 100644
--- a/lib/Format/WhitespaceManager.h
+++ b/lib/Format/WhitespaceManager.h
@@ -57,6 +57,8 @@ public:
   /// was not called.
   void addUntouchableToken(const FormatToken &Tok, bool InPPDirective);
 
+  llvm::Error addReplacement(const tooling::Replacement &Replacement);
+
   /// \brief Inserts or replaces whitespace in the middle of a token.
   ///
   /// Inserts \p PreviousPostfix, \p Newlines, \p Spaces and \p CurrentPrefix
@@ -194,9 +196,9 @@ private:
   /// \brief Stores \p Text as the replacement for the whitespace in \p Range.
   void storeReplacement(SourceRange Range, StringRef Text);
   void appendNewlineText(std::string &Text, unsigned Newlines);
-  void appendNewlineText(std::string &Text, unsigned Newlines,
-                         unsigned PreviousEndOfTokenColumn,
-                         unsigned EscapedNewlineColumn);
+  void appendEscapedNewlineText(std::string &Text, unsigned Newlines,
+                                unsigned PreviousEndOfTokenColumn,
+                                unsigned EscapedNewlineColumn);
   void appendIndentText(std::string &Text, unsigned IndentLevel,
                         unsigned Spaces, unsigned WhitespaceStartColumn);