Index: lib/CodeGen/AsmPrinter/DwarfAccelTable.h
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfAccelTable.h
+++ lib/CodeGen/AsmPrinter/DwarfAccelTable.h
@@ -162,19 +162,37 @@
 public:
   struct HashDataContents {
     const DIE *Die;   // Offsets
-    char Flags; // Specific flags to output
 
-    HashDataContents(const DIE *D, char Flags) : Die(D), Flags(Flags) {}
+    HashDataContents(const DIE *D) : Die(D) {}
 
 #ifndef NDEBUG
     void print(raw_ostream &OS) const {
-      OS << "  Offset: " << Die->getOffset() << "\n"
-         << "  Tag: " << dwarf::TagString(Die->getTag()) << "\n"
-         << "  Flags: " << Flags << "\n";
+      OS << "  Offset: " << Die->getOffset() << "\n";
+      OS << "  Tag: " << dwarf::TagString(Die->getTag()) << "\n";
     }
 #endif
   };
 
+  using DataForAtomFunction =
+      std::function<uint64_t(const HashDataContents &, unsigned)>;
+  static uint64_t DefaultGetDataForAtom(const HashDataContents &HDC,
+                                        unsigned AtomIdx) {
+    switch (AtomIdx) {
+    // First atom is a DIE offset.
+    case 0:
+      return HDC.Die->getDebugSectionOffset();
+    // Second atom is a DIE offset.
+    case 1:
+      return HDC.Die->getTag();
+    // Third atom is a flag field that's always zero.
+    case 2:
+      return 0;
+    default:
+      break;
+    }
+    return 0;
+  }
+
 private:
   // String Data
   struct DataArray {
@@ -206,9 +224,7 @@
         OS << "<none>";
       OS << "\n";
       for (HashDataContents *C : Data.Values) {
-        OS << "  Offset: " << C->Die->getOffset() << "\n";
-        OS << "  Tag: " << dwarf::TagString(C->Die->getTag()) << "\n";
-        OS << "  Flags: " << C->Flags << "\n";
+        C->print(OS);
       }
     }
 
@@ -231,25 +247,28 @@
   TableHeaderData HeaderData;
   std::vector<HashData *> Data;
 
-  using StringEntries = StringMap<DataArray, BumpPtrAllocator &>;
+  DataForAtomFunction DataForAtom;
 
+  using StringEntries = StringMap<DataArray, BumpPtrAllocator &>;
   StringEntries Entries;
 
-  // Buckets/Hashes/Offsets
   using HashList = std::vector<HashData *>;
+  HashList Hashes;
+
   using BucketList = std::vector<HashList>;
   BucketList Buckets;
-  HashList Hashes;
 
   // Public Implementation
 public:
-  DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom>);
+  DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom>,
+                  DataForAtomFunction DataForAtom = DefaultGetDataForAtom);
   DwarfAccelTable(const DwarfAccelTable &) = delete;
   DwarfAccelTable &operator=(const DwarfAccelTable &) = delete;
 
-  void AddName(DwarfStringPoolEntryRef Name, const DIE *Die, char Flags = 0);
+  void AddName(DwarfStringPoolEntryRef Name, const DIE *Die);
   void FinalizeTable(AsmPrinter *, StringRef);
   void emit(AsmPrinter *, const MCSymbol *, DwarfDebug *);
+
 #ifndef NDEBUG
   void print(raw_ostream &OS);
   void dump() { print(dbgs()); }
Index: lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp
+++ lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp
@@ -31,20 +31,36 @@
 
 using namespace llvm;
 
+/// Return the size (in bytes) for the given Form.
+static unsigned GetSizeForForm(uint16_t Form) {
+  switch (Form) {
+  case dwarf::DW_FORM_data1:
+    return 1;
+  case dwarf::DW_FORM_data2:
+    return 2;
+  case dwarf::DW_FORM_data4:
+    return 4;
+  case dwarf::DW_FORM_data8:
+    return 8;
+  default:
+    llvm_unreachable("Unsupported atom type");
+  }
+}
+
 // The length of the header data is always going to be 4 + 4 + 4*NumAtoms.
-DwarfAccelTable::DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom> atomList)
-    : Header(8 + (atomList.size() * 4)), HeaderData(atomList),
-      Entries(Allocator) {}
+DwarfAccelTable::DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom> AtomList,
+                                 DataForAtomFunction DataForAtom)
+    : Header(8 + (AtomList.size() * 4)), HeaderData(AtomList),
+      DataForAtom(std::move(DataForAtom)), Entries(Allocator) {}
 
-void DwarfAccelTable::AddName(DwarfStringPoolEntryRef Name, const DIE *die,
-                              char Flags) {
+void DwarfAccelTable::AddName(DwarfStringPoolEntryRef Name, const DIE *die) {
   assert(Data.empty() && "Already finalized!");
   // If the string is in the list already then add this die to the list
   // otherwise add a new one.
   DataArray &DIEs = Entries[Name.getString()];
   assert(!DIEs.Name || DIEs.Name == Name);
   DIEs.Name = Name;
-  DIEs.Values.push_back(new (Allocator) HashDataContents(die, Flags));
+  DIEs.Values.push_back(new (Allocator) HashDataContents(die));
 }
 
 void DwarfAccelTable::ComputeBucketCount() {
@@ -68,7 +84,7 @@
   Header.hashes_count = num;
 }
 
-// compareDIEs - comparison predicate that sorts DIEs by their offset.
+/// Comparison predicate that sorts DIEs by their offset.
 static bool compareDIEs(const DwarfAccelTable::HashDataContents *A,
                         const DwarfAccelTable::HashDataContents *B) {
   return A->Die->getOffset() < B->Die->getOffset();
@@ -227,13 +243,12 @@
       Asm->OutStreamer->AddComment("Num DIEs");
       Asm->EmitInt32((*HI)->Data.Values.size());
       for (HashDataContents *HD : (*HI)->Data.Values) {
-        // Emit the DIE offset
-        Asm->EmitInt32(HD->Die->getDebugSectionOffset());
-        // If we have multiple Atoms emit that info too.
-        // FIXME: A bit of a hack, we either emit only one atom or all info.
-        if (HeaderData.Atoms.size() > 1) {
-          Asm->EmitInt16(HD->Die->getTag());
-          Asm->EmitInt8(HD->Flags);
+        // Emit data for Atoms.
+        unsigned AtomIdx = 0;
+        for (auto Atom : HeaderData.Atoms) {
+          Asm->OutStreamer->EmitIntValue(DataForAtom(*HD, AtomIdx),
+                                         GetSizeForForm(Atom.form));
+          AtomIdx++;
         }
       }
       PrevHash = (*HI)->HashValue;