Index: include/llvm/DebugInfo/DWARF/DWARFFormValue.h
===================================================================
--- include/llvm/DebugInfo/DWARF/DWARFFormValue.h
+++ include/llvm/DebugInfo/DWARF/DWARFFormValue.h
@@ -49,40 +49,41 @@
     const uint8_t* data;
   };
 
-  dwarf::Form Form;   // Form for this value.
+  dwarf::Form Form; // Form for this value.
   ValueType Value; // Contains all data for the form.
+  const DWARFUnit *U; // Remember the DWARFUnit at extract time.
 
 public:
-  DWARFFormValue(dwarf::Form F = dwarf::Form(0)) : Form(F) {}
+  DWARFFormValue(dwarf::Form F = dwarf::Form(0)) : Form(F), U(nullptr) {}
   dwarf::Form getForm() const { return Form; }
   bool isFormClass(FormClass FC) const;
+  const DWARFUnit *getUnit() const { return U; }
+  void dump(raw_ostream &OS) const;
 
-  void dump(raw_ostream &OS, const DWARFUnit *U) const;
-
   /// \brief extracts a value in data at offset *offset_ptr.
   ///
   /// The passed DWARFUnit is allowed to be nullptr, in which
   /// case no relocation processing will be performed and some
   /// kind of forms that depend on Unit information are disallowed.
   /// \returns whether the extraction succeeded.
-  bool extractValue(DataExtractor data, uint32_t *offset_ptr,
-                    const DWARFUnit *u);
+  bool extractValue(const DataExtractor &Data, uint32_t *OffsetPtr,
+                    const DWARFUnit *U);
   bool isInlinedCStr() const {
     return Value.data != nullptr && Value.data == (const uint8_t*)Value.cstr;
   }
 
   /// getAsFoo functions below return the extracted value as Foo if only
   /// DWARFFormValue has form class is suitable for representing Foo.
-  Optional<uint64_t> getAsReference(const DWARFUnit *U) const;
+  Optional<uint64_t> getAsReference() const;
   Optional<uint64_t> getAsUnsignedConstant() const;
   Optional<int64_t> getAsSignedConstant() const;
-  Optional<const char *> getAsCString(const DWARFUnit *U) const;
-  Optional<uint64_t> getAsAddress(const DWARFUnit *U) const;
+  Optional<const char *> getAsCString() const;
+  Optional<uint64_t> getAsAddress() const;
   Optional<uint64_t> getAsSectionOffset() const;
   Optional<ArrayRef<uint8_t>> getAsBlock() const;
 
   bool skipValue(DataExtractor debug_info_data, uint32_t *offset_ptr,
-                 const DWARFUnit *u) const;
+                 const DWARFUnit *U) const;
   static bool skipValue(dwarf::Form form, DataExtractor debug_info_data,
                         uint32_t *offset_ptr, const DWARFUnit *u);
   static bool skipValue(dwarf::Form form, DataExtractor debug_info_data,
@@ -92,7 +93,7 @@
   static ArrayRef<uint8_t> getFixedFormSizes(uint8_t AddrSize,
                                              uint16_t Version);
 private:
-  void dumpString(raw_ostream &OS, const DWARFUnit *U) const;
+  void dumpString(raw_ostream &OS) const;
 };
 
 }
Index: include/llvm/DebugInfo/DWARF/DWARFUnit.h
===================================================================
--- include/llvm/DebugInfo/DWARF/DWARFUnit.h
+++ include/llvm/DebugInfo/DWARF/DWARFUnit.h
@@ -195,6 +195,10 @@
     return Abbrevs;
   }
   uint8_t getAddressByteSize() const { return AddrSize; }
+  uint8_t getRefAddrByteSize() const {
+    // FIXME: Support DWARF64.
+    return (Version == 2) ? AddrSize : 4;
+  }
   uint64_t getBaseAddress() const { return BaseAddr; }
 
   void setBaseAddress(uint64_t base_addr) {
Index: lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
+++ lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
@@ -120,7 +120,7 @@
           for (auto &Atom : AtomForms) {
             OS << format("{Atom[%d]: ", i++);
             if (Atom.extractValue(AccelSection, &DataOffset, nullptr))
-              Atom.dump(OS, nullptr);
+              Atom.dump(OS);
             else
               OS << "Error extracting the value";
             OS << "} ";
Index: lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
+++ lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
@@ -158,13 +158,13 @@
   else if (attr == DW_AT_decl_line || attr == DW_AT_call_line)
     OS << *formValue.getAsUnsignedConstant();
   else
-    formValue.dump(OS, u);
+    formValue.dump(OS);
 
   // We have dumped the attribute raw value. For some attributes
   // having both the raw value and the pretty-printed value is
   // interesting. These attributes are handled below.
   if (attr == DW_AT_specification || attr == DW_AT_abstract_origin) {
-    Optional<uint64_t> Ref = formValue.getAsReference(u);
+    Optional<uint64_t> Ref = formValue.getAsReference();
     if (Ref.hasValue()) {
       uint32_t RefOffset = Ref.getValue();
       DWARFDebugInfoEntryMinimal DIE;
@@ -264,7 +264,7 @@
   DWARFFormValue FormValue;
   if (!getAttributeValue(U, Attr, FormValue))
     return FailValue;
-  Optional<const char *> Result = FormValue.getAsCString(U);
+  Optional<const char *> Result = FormValue.getAsCString();
   return Result.hasValue() ? Result.getValue() : FailValue;
 }
 
@@ -274,7 +274,7 @@
   DWARFFormValue FormValue;
   if (!getAttributeValue(U, Attr, FormValue))
     return FailValue;
-  Optional<uint64_t> Result = FormValue.getAsAddress(U);
+  Optional<uint64_t> Result = FormValue.getAsAddress();
   return Result.hasValue() ? Result.getValue() : FailValue;
 }
 
@@ -294,7 +294,7 @@
   DWARFFormValue FormValue;
   if (!getAttributeValue(U, Attr, FormValue))
     return FailValue;
-  Optional<uint64_t> Result = FormValue.getAsReference(U);
+  Optional<uint64_t> Result = FormValue.getAsReference();
   return Result.hasValue() ? Result.getValue() : FailValue;
 }
 
Index: lib/DebugInfo/DWARF/DWARFFormValue.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFFormValue.cpp
+++ lib/DebugInfo/DWARF/DWARFFormValue.cpp
@@ -133,8 +133,10 @@
          FC == FC_SectionOffset;
 }
 
-bool DWARFFormValue::extractValue(DataExtractor data, uint32_t *offset_ptr,
+bool DWARFFormValue::extractValue(const DataExtractor &data, 
+                                  uint32_t *offset_ptr,
                                   const DWARFUnit *cu) {
+  U = cu;
   bool indirect = false;
   bool is_block = false;
   Value.data = nullptr;
@@ -145,14 +147,14 @@
     switch (Form) {
     case DW_FORM_addr:
     case DW_FORM_ref_addr: {
-      if (!cu)
+      if (!U)
         return false;
       uint16_t AddrSize =
           (Form == DW_FORM_addr)
-              ? cu->getAddressByteSize()
-              : getRefAddrSize(cu->getAddressByteSize(), cu->getVersion());
-      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr);
-      if (AI != cu->getRelocMap()->end()) {
+              ? U->getAddressByteSize()
+              : U->getRefAddrByteSize();
+      RelocAddrMap::const_iterator AI = U->getRelocMap()->find(*offset_ptr);
+      if (AI != U->getRelocMap()->end()) {
         const std::pair<uint8_t, int64_t> &R = AI->second;
         Value.uval = data.getUnsigned(offset_ptr, AddrSize) + R.second;
       } else
@@ -188,10 +190,10 @@
     case DW_FORM_data4:
     case DW_FORM_ref4: {
       Value.uval = data.getU32(offset_ptr);
-      if (!cu)
+      if (!U)
         break;
-      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr-4);
-      if (AI != cu->getRelocMap()->end())
+      RelocAddrMap::const_iterator AI = U->getRelocMap()->find(*offset_ptr-4);
+      if (AI != U->getRelocMap()->end())
         Value.uval += AI->second.second;
       break;
     }
@@ -219,11 +221,11 @@
     case DW_FORM_GNU_strp_alt: {
       // FIXME: This is 64-bit for DWARF64.
       Value.uval = data.getU32(offset_ptr);
-      if (!cu)
+      if (!U)
         break;
       RelocAddrMap::const_iterator AI =
-          cu->getRelocMap()->find(*offset_ptr - 4);
-      if (AI != cu->getRelocMap()->end())
+          U->getRelocMap()->find(*offset_ptr - 4);
+      if (AI != U->getRelocMap()->end())
         Value.uval += AI->second.second;
       break;
     }
@@ -256,8 +258,8 @@
 
 bool
 DWARFFormValue::skipValue(DataExtractor debug_info_data, uint32_t* offset_ptr,
-                          const DWARFUnit *cu) const {
-  return DWARFFormValue::skipValue(Form, debug_info_data, offset_ptr, cu);
+                          const DWARFUnit *U) const {
+  return DWARFFormValue::skipValue(Form, debug_info_data, offset_ptr, U);
 }
 
 bool
@@ -371,7 +373,7 @@
 }
 
 void
-DWARFFormValue::dump(raw_ostream &OS, const DWARFUnit *cu) const {
+DWARFFormValue::dump(raw_ostream &OS) const {
   uint64_t uvalue = Value.uval;
   bool cu_relative_offset = false;
 
@@ -380,7 +382,9 @@
   case DW_FORM_GNU_addr_index: {
     OS << format(" indexed (%8.8x) address = ", (uint32_t)uvalue);
     uint64_t Address;
-    if (cu->getAddrOffsetSectionItem(uvalue, Address))
+    if (U == nullptr)
+      OS << "<invalid dwarf unit>";
+    else if (U->getAddrOffsetSectionItem(uvalue, Address))
       OS << format("0x%016" PRIx64, Address);
     else
       OS << "<no .debug_addr section>";
@@ -431,17 +435,17 @@
   case DW_FORM_udata:     OS << Value.uval; break;
   case DW_FORM_strp: {
     OS << format(" .debug_str[0x%8.8x] = ", (uint32_t)uvalue);
-    dumpString(OS, cu);
+    dumpString(OS);
     break;
   }
   case DW_FORM_GNU_str_index: {
     OS << format(" indexed (%8.8x) string = ", (uint32_t)uvalue);
-    dumpString(OS, cu);
+    dumpString(OS);
     break;
   }
   case DW_FORM_GNU_strp_alt: {
     OS << format("alt indirect string, offset: 0x%" PRIx64 "", uvalue);
-    dumpString(OS, cu);
+    dumpString(OS);
     break;
   }
   case DW_FORM_ref_addr:
@@ -490,13 +494,13 @@
   if (cu_relative_offset) {
     OS << " => {";
     WithColor(OS, syntax::Address).get()
-      << format("0x%8.8" PRIx64, uvalue + (cu ? cu->getOffset() : 0));
+      << format("0x%8.8" PRIx64, uvalue + (U ? U->getOffset() : 0));
     OS << "}";
   }
 }
 
-void DWARFFormValue::dumpString(raw_ostream &OS, const DWARFUnit *U) const {
-  Optional<const char *> DbgStr = getAsCString(U);
+void DWARFFormValue::dumpString(raw_ostream &OS) const {
+  Optional<const char *> DbgStr = getAsCString();
   if (DbgStr.hasValue()) {
     raw_ostream &COS = WithColor(OS, syntax::String);
     COS << '"';
@@ -505,7 +509,7 @@
   }
 }
 
-Optional<const char *> DWARFFormValue::getAsCString(const DWARFUnit *U) const {
+Optional<const char *> DWARFFormValue::getAsCString() const {
   if (!isFormClass(FC_String))
     return None;
   if (Form == DW_FORM_string)
@@ -526,7 +530,7 @@
   return None;
 }
 
-Optional<uint64_t> DWARFFormValue::getAsAddress(const DWARFUnit *U) const {
+Optional<uint64_t> DWARFFormValue::getAsAddress() const {
   if (!isFormClass(FC_Address))
     return None;
   if (Form == DW_FORM_GNU_addr_index) {
@@ -539,7 +543,7 @@
   return Value.uval;
 }
 
-Optional<uint64_t> DWARFFormValue::getAsReference(const DWARFUnit *U) const {
+Optional<uint64_t> DWARFFormValue::getAsReference() const {
   if (!isFormClass(FC_Reference))
     return None;
   switch (Form) {
Index: lib/DebugInfo/DWARF/DWARFTypeUnit.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFTypeUnit.cpp
+++ lib/DebugInfo/DWARF/DWARFTypeUnit.cpp
@@ -30,7 +30,7 @@
   DWARFFormValue NameVal;
   const char *Name = "";
   if (TD->getAttributeValue(this, llvm::dwarf::DW_AT_name, NameVal))
-    if (auto ON = NameVal.getAsCString(this))
+    if (auto ON = NameVal.getAsCString())
       Name = *ON;
 
   if (SummarizeTypes) {
Index: tools/dsymutil/DwarfLinker.cpp
===================================================================
--- tools/dsymutil/DwarfLinker.cpp
+++ tools/dsymutil/DwarfLinker.cpp
@@ -1487,7 +1487,7 @@
     const DWARFFormValue &RefValue, const DWARFUnit &Unit,
     const DWARFDebugInfoEntryMinimal &DIE, CompileUnit *&RefCU) {
   assert(RefValue.isFormClass(DWARFFormValue::FC_Reference));
-  uint64_t RefOffset = *RefValue.getAsReference(&Unit);
+  uint64_t RefOffset = *RefValue.getAsReference();
 
   if ((RefCU = getUnitForOffset(Units, RefOffset)))
     if (const auto *RefDie = RefCU->getOrigUnit().getDIEForOffset(RefOffset))
@@ -2159,7 +2159,7 @@
 
   uint64_t HighPc;
   if (HighPcValue.isFormClass(DWARFFormValue::FC_Address)) {
-    HighPc = *HighPcValue.getAsAddress(&OrigUnit);
+    HighPc = *HighPcValue.getAsAddress();
   } else {
     assert(HighPcValue.isFormClass(DWARFFormValue::FC_Constant));
     HighPc = LowPc + *HighPcValue.getAsUnsignedConstant();
@@ -2357,7 +2357,7 @@
                                                       const DWARFFormValue &Val,
                                                       const DWARFUnit &U) {
   // Switch everything to out of line strings.
-  const char *String = *Val.getAsCString(&U);
+  const char *String = *Val.getAsCString();
   unsigned Offset = Linker.StringPool.getStringOffset(String);
   Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr), dwarf::DW_FORM_strp,
                DIEInteger(Offset));
@@ -2369,7 +2369,7 @@
     AttributeSpec AttrSpec, unsigned AttrSize, const DWARFFormValue &Val,
     CompileUnit &Unit) {
   const DWARFUnit &U = Unit.getOrigUnit();
-  uint32_t Ref = *Val.getAsReference(&U);
+  uint32_t Ref = *Val.getAsReference();
   DIE *NewRefDie = nullptr;
   CompileUnit *RefUnit = nullptr;
   DeclContext *Ctxt = nullptr;
@@ -2481,7 +2481,7 @@
 unsigned DwarfLinker::DIECloner::cloneAddressAttribute(
     DIE &Die, AttributeSpec AttrSpec, const DWARFFormValue &Val,
     const CompileUnit &Unit, AttributesInfo &Info) {
-  uint64_t Addr = *Val.getAsAddress(&Unit.getOrigUnit());
+  uint64_t Addr = *Val.getAsAddress();
   if (AttrSpec.Attr == dwarf::DW_AT_low_pc) {
     if (Die.getTag() == dwarf::DW_TAG_inlined_subroutine ||
         Die.getTag() == dwarf::DW_TAG_lexical_block)