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diff --git a/include/llvm/DebugInfo/DWARF/DWARFUnit.h b/include/llvm/DebugInfo/DWARF/DWARFUnit.h
new file mode 100644
index 000000000000..5604b93f2205
--- /dev/null
+++ b/include/llvm/DebugInfo/DWARF/DWARFUnit.h
@@ -0,0 +1,284 @@
+//===-- DWARFUnit.h ---------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_DEBUGINFO_DWARFUNIT_H
+#define LLVM_LIB_DEBUGINFO_DWARFUNIT_H
+
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
+#include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
+#include "llvm/DebugInfo/DWARF/DWARFDebugRangeList.h"
+#include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
+#include "llvm/DebugInfo/DWARF/DWARFSection.h"
+#include <vector>
+
+namespace llvm {
+
+namespace object {
+class ObjectFile;
+}
+
+class DWARFContext;
+class DWARFDebugAbbrev;
+class DWARFUnit;
+class StringRef;
+class raw_ostream;
+
+/// Base class for all DWARFUnitSection classes. This provides the
+/// functionality common to all unit types.
+class DWARFUnitSectionBase {
+public:
+  /// Returns the Unit that contains the given section offset in the
+  /// same section this Unit originated from.
+  virtual DWARFUnit *getUnitForOffset(uint32_t Offset) const = 0;
+
+  void parse(DWARFContext &C, const DWARFSection &Section);
+  void parseDWO(DWARFContext &C, const DWARFSection &DWOSection);
+
+protected:
+  virtual void parseImpl(DWARFContext &Context, const DWARFSection &Section,
+                         const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
+                         StringRef SOS, StringRef AOS, bool isLittleEndian) = 0;
+
+  ~DWARFUnitSectionBase() = default;
+};
+
+/// Concrete instance of DWARFUnitSection, specialized for one Unit type.
+template<typename UnitType>
+class DWARFUnitSection final : public SmallVector<std::unique_ptr<UnitType>, 1>,
+                               public DWARFUnitSectionBase {
+
+  struct UnitOffsetComparator {
+    bool operator()(uint32_t LHS,
+                    const std::unique_ptr<UnitType> &RHS) const {
+      return LHS < RHS->getNextUnitOffset();
+    }
+  };
+
+  bool Parsed;
+
+public:
+  DWARFUnitSection() : Parsed(false) {}
+  DWARFUnitSection(DWARFUnitSection &&DUS) :
+    SmallVector<std::unique_ptr<UnitType>, 1>(std::move(DUS)), Parsed(DUS.Parsed) {}
+
+  typedef llvm::SmallVectorImpl<std::unique_ptr<UnitType>> UnitVector;
+  typedef typename UnitVector::iterator iterator;
+  typedef llvm::iterator_range<typename UnitVector::iterator> iterator_range;
+
+  UnitType *getUnitForOffset(uint32_t Offset) const override {
+    auto *CU = std::upper_bound(this->begin(), this->end(), Offset,
+                                UnitOffsetComparator());
+    if (CU != this->end())
+      return CU->get();
+    return nullptr;
+  }
+
+private:
+  void parseImpl(DWARFContext &Context, const DWARFSection &Section,
+                 const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
+                 StringRef SOS, StringRef AOS, bool LE) override {
+    if (Parsed)
+      return;
+    DataExtractor Data(Section.Data, LE, 0);
+    uint32_t Offset = 0;
+    while (Data.isValidOffset(Offset)) {
+      auto U = llvm::make_unique<UnitType>(Context, Section, DA, RS, SS, SOS,
+                                           AOS, LE, *this);
+      if (!U->extract(Data, &Offset))
+        break;
+      this->push_back(std::move(U));
+      Offset = this->back()->getNextUnitOffset();
+    }
+    Parsed = true;
+  }
+};
+
+class DWARFUnit {
+  DWARFContext &Context;
+  // Section containing this DWARFUnit.
+  const DWARFSection &InfoSection;
+
+  const DWARFDebugAbbrev *Abbrev;
+  StringRef RangeSection;
+  uint32_t RangeSectionBase;
+  StringRef StringSection;
+  StringRef StringOffsetSection;
+  StringRef AddrOffsetSection;
+  uint32_t AddrOffsetSectionBase;
+  bool isLittleEndian;
+  const DWARFUnitSectionBase &UnitSection;
+
+  uint32_t Offset;
+  uint32_t Length;
+  uint16_t Version;
+  const DWARFAbbreviationDeclarationSet *Abbrevs;
+  uint8_t AddrSize;
+  uint64_t BaseAddr;
+  // The compile unit debug information entry items.
+  std::vector<DWARFDebugInfoEntryMinimal> DieArray;
+
+  class DWOHolder {
+    object::OwningBinary<object::ObjectFile> DWOFile;
+    std::unique_ptr<DWARFContext> DWOContext;
+    DWARFUnit *DWOU;
+  public:
+    DWOHolder(StringRef DWOPath);
+    DWARFUnit *getUnit() const { return DWOU; }
+  };
+  std::unique_ptr<DWOHolder> DWO;
+
+protected:
+  virtual bool extractImpl(DataExtractor debug_info, uint32_t *offset_ptr);
+  /// Size in bytes of the unit header.
+  virtual uint32_t getHeaderSize() const { return 11; }
+
+public:
+  DWARFUnit(DWARFContext &Context, const DWARFSection &Section,
+            const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
+            StringRef SOS, StringRef AOS, bool LE,
+            const DWARFUnitSectionBase &UnitSection);
+
+  virtual ~DWARFUnit();
+
+  DWARFContext& getContext() const { return Context; }
+
+  StringRef getStringSection() const { return StringSection; }
+  StringRef getStringOffsetSection() const { return StringOffsetSection; }
+  void setAddrOffsetSection(StringRef AOS, uint32_t Base) {
+    AddrOffsetSection = AOS;
+    AddrOffsetSectionBase = Base;
+  }
+  void setRangesSection(StringRef RS, uint32_t Base) {
+    RangeSection = RS;
+    RangeSectionBase = Base;
+  }
+
+  bool getAddrOffsetSectionItem(uint32_t Index, uint64_t &Result) const;
+  // FIXME: Result should be uint64_t in DWARF64.
+  bool getStringOffsetSectionItem(uint32_t Index, uint32_t &Result) const;
+
+  DataExtractor getDebugInfoExtractor() const {
+    return DataExtractor(InfoSection.Data, isLittleEndian, AddrSize);
+  }
+  DataExtractor getStringExtractor() const {
+    return DataExtractor(StringSection, false, 0);
+  }
+
+  const RelocAddrMap *getRelocMap() const { return &InfoSection.Relocs; }
+
+  bool extract(DataExtractor debug_info, uint32_t* offset_ptr);
+
+  /// extractRangeList - extracts the range list referenced by this compile
+  /// unit from .debug_ranges section. Returns true on success.
+  /// Requires that compile unit is already extracted.
+  bool extractRangeList(uint32_t RangeListOffset,
+                        DWARFDebugRangeList &RangeList) const;
+  void clear();
+  uint32_t getOffset() const { return Offset; }
+  uint32_t getNextUnitOffset() const { return Offset + Length + 4; }
+  uint32_t getLength() const { return Length; }
+  uint16_t getVersion() const { return Version; }
+  const DWARFAbbreviationDeclarationSet *getAbbreviations() const {
+    return Abbrevs;
+  }
+  uint8_t getAddressByteSize() const { return AddrSize; }
+  uint64_t getBaseAddress() const { return BaseAddr; }
+
+  void setBaseAddress(uint64_t base_addr) {
+    BaseAddr = base_addr;
+  }
+
+  const DWARFDebugInfoEntryMinimal *getUnitDIE(bool ExtractUnitDIEOnly = true) {
+    extractDIEsIfNeeded(ExtractUnitDIEOnly);
+    return DieArray.empty() ? nullptr : &DieArray[0];
+  }
+
+  const char *getCompilationDir();
+  uint64_t getDWOId();
+
+  void collectAddressRanges(DWARFAddressRangesVector &CURanges);
+
+  /// getInlinedChainForAddress - fetches inlined chain for a given address.
+  /// Returns empty chain if there is no subprogram containing address. The
+  /// chain is valid as long as parsed compile unit DIEs are not cleared.
+  DWARFDebugInfoEntryInlinedChain getInlinedChainForAddress(uint64_t Address);
+
+  /// getUnitSection - Return the DWARFUnitSection containing this unit.
+  const DWARFUnitSectionBase &getUnitSection() const { return UnitSection; }
+
+  /// \brief Returns the number of DIEs in the unit. Parses the unit
+  /// if necessary.
+  unsigned getNumDIEs() {
+    extractDIEsIfNeeded(false);
+    return DieArray.size();
+  }
+
+  /// \brief Return the index of a DIE inside the unit's DIE vector.
+  ///
+  /// It is illegal to call this method with a DIE that hasn't be
+  /// created by this unit. In other word, it's illegal to call this
+  /// method on a DIE that isn't accessible by following
+  /// children/sibling links starting from this unit's getUnitDIE().
+  uint32_t getDIEIndex(const DWARFDebugInfoEntryMinimal *DIE) {
+    assert(!DieArray.empty() && DIE >= &DieArray[0] &&
+           DIE < &DieArray[0] + DieArray.size());
+    return DIE - &DieArray[0];
+  }
+
+  /// \brief Return the DIE object at the given index.
+  const DWARFDebugInfoEntryMinimal *getDIEAtIndex(unsigned Index) const {
+    assert(Index < DieArray.size());
+    return &DieArray[Index];
+  }
+
+  /// \brief Return the DIE object for a given offset inside the
+  /// unit's DIE vector.
+  ///
+  /// The unit needs to have his DIEs extracted for this method to work.
+  const DWARFDebugInfoEntryMinimal *getDIEForOffset(uint32_t Offset) const {
+    assert(!DieArray.empty());
+    auto it = std::lower_bound(
+        DieArray.begin(), DieArray.end(), Offset,
+        [=](const DWARFDebugInfoEntryMinimal &LHS, uint32_t Offset) {
+          return LHS.getOffset() < Offset;
+        });
+    return it == DieArray.end() ? nullptr : &*it;
+  }
+
+private:
+  /// Size in bytes of the .debug_info data associated with this compile unit.
+  size_t getDebugInfoSize() const { return Length + 4 - getHeaderSize(); }
+
+  /// extractDIEsIfNeeded - Parses a compile unit and indexes its DIEs if it
+  /// hasn't already been done. Returns the number of DIEs parsed at this call.
+  size_t extractDIEsIfNeeded(bool CUDieOnly);
+  /// extractDIEsToVector - Appends all parsed DIEs to a vector.
+  void extractDIEsToVector(bool AppendCUDie, bool AppendNonCUDIEs,
+                           std::vector<DWARFDebugInfoEntryMinimal> &DIEs) const;
+  /// setDIERelations - We read in all of the DIE entries into our flat list
+  /// of DIE entries and now we need to go back through all of them and set the
+  /// parent, sibling and child pointers for quick DIE navigation.
+  void setDIERelations();
+  /// clearDIEs - Clear parsed DIEs to keep memory usage low.
+  void clearDIEs(bool KeepCUDie);
+
+  /// parseDWO - Parses .dwo file for current compile unit. Returns true if
+  /// it was actually constructed.
+  bool parseDWO();
+
+  /// getSubprogramForAddress - Returns subprogram DIE with address range
+  /// encompassing the provided address. The pointer is alive as long as parsed
+  /// compile unit DIEs are not cleared.
+  const DWARFDebugInfoEntryMinimal *getSubprogramForAddress(uint64_t Address);
+};
+
+}
+
+#endif