Index: llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2962,21 +2962,22 @@
 #define HANDLE_MACRO_FLAG(ID, NAME) MACRO_FLAG_##NAME = ID,
 #include "llvm/BinaryFormat/Dwarf.def"
   };
-  uint8_t Flags = 0;
   Asm->OutStreamer->AddComment("Macro information version");
   Asm->emitInt16(DwarfVersion >= 5 ? DwarfVersion : 4);
-  // We are setting Offset and line offset flags unconditionally here,
-  // since we're only supporting DWARF32 and line offset should be mostly
-  // present.
-  // FIXME: Add support for DWARF64.
-  Flags |= MACRO_FLAG_DEBUG_LINE_OFFSET;
-  Asm->OutStreamer->AddComment("Flags: 32 bit, debug_line_offset present");
-  Asm->emitInt8(Flags);
+  // We emit the line offset flag unconditionally here, since line offset should
+  // be mostly present.
+  if (Asm->isDwarf64()) {
+    Asm->OutStreamer->AddComment("Flags: 64 bit, debug_line_offset present");
+    Asm->emitInt8(MACRO_FLAG_OFFSET_SIZE | MACRO_FLAG_DEBUG_LINE_OFFSET);
+  } else {
+    Asm->OutStreamer->AddComment("Flags: 32 bit, debug_line_offset present");
+    Asm->emitInt8(MACRO_FLAG_DEBUG_LINE_OFFSET);
+  }
   Asm->OutStreamer->AddComment("debug_line_offset");
   if (DD.useSplitDwarf())
-    Asm->OutStreamer->emitIntValue(0, /*Size=*/4);
+    Asm->emitDwarfLengthOrOffset(0);
   else
-    Asm->OutStreamer->emitSymbolValue(CU.getLineTableStartSym(), /*Size=*/4);
+    Asm->emitDwarfSymbolReference(CU.getLineTableStartSym());
 }
 
 void DwarfDebug::handleMacroNodes(DIMacroNodeArray Nodes, DwarfCompileUnit &U) {
@@ -3019,10 +3020,8 @@
       Asm->OutStreamer->AddComment("Line Number");
       Asm->emitULEB128(M.getLine());
       Asm->OutStreamer->AddComment("Macro String");
-      // FIXME: Add support for DWARF64.
-      Asm->OutStreamer->emitSymbolValue(
-          InfoHolder.getStringPool().getEntry(*Asm, Str).getSymbol(),
-          /*Size=*/4);
+      Asm->emitDwarfSymbolReference(
+          InfoHolder.getStringPool().getEntry(*Asm, Str).getSymbol());
     }
   } else {
     Asm->OutStreamer->AddComment(dwarf::MacinfoString(M.getMacinfoType()));
Index: llvm/test/DebugInfo/X86/debug-macro-dwarf64.ll
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/X86/debug-macro-dwarf64.ll
@@ -0,0 +1,34 @@
+; This checks that .debug_macro[.dwo] can be generated in the DWARF64 format.
+
+; RUN: llc -mtriple=x86_64 -dwarf-version=4 -dwarf64 -use-gnu-debug-macro -filetype=obj %s -o %t
+; RUN: llvm-dwarfdump -debug-macro %t | FileCheck %s --check-prefix=DWARF4
+
+; RUN: llc -mtriple=x86_64 -dwarf-version=5 -dwarf64 -filetype=obj %s -o %t
+; RUN: llvm-dwarfdump -debug-macro %t | FileCheck %s --check-prefix=DWARF5
+
+; RUN: llc -mtriple=x86_64 -dwarf-version=5 -dwarf64 -split-dwarf-file=foo.dwo -filetype=obj %s -o %t
+; RUN: llvm-dwarfdump -debug-macro %t | FileCheck %s --check-prefixes=DWARF5,DWO
+
+; DWARF4:      .debug_macro contents:
+; DWARF4-NEXT: 0x00000000:
+; DWARF4-NEXT: macro header: version = 0x0004, flags = 0x03, format = DWARF64, debug_line_offset = 0x0000000000000000
+; DWARF4-NEXT: DW_MACRO_GNU_define_indirect - lineno: 2 macro: FOO 1
+; DWARF4-NEXT: DW_MACRO_GNU_undef_indirect - lineno: 5 macro: BAR
+
+; DWARF5:      .debug_macro contents:
+; DWO:         .debug_macro.dwo contents:
+; DWARF5-NEXT: 0x00000000:
+; DWARF5-NEXT: macro header: version = 0x0005, flags = 0x03, format = DWARF64, debug_line_offset = 0x0000000000000000
+; DWARF5-NEXT: DW_MACRO_define_strx - lineno: 2 macro: FOO 1
+; DWARF5-NEXT: DW_MACRO_undef_strx - lineno: 5 macro: BAR
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+!1 = !DIFile(filename: "foo.c", directory: "/tmp")
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "Manual", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !3, globals: !3, macros: !4)
+!3 = !{}
+!4 = !{!5, !6}
+!5 = !DIMacro(type: DW_MACINFO_define, line: 2, name: "FOO", value: "1")
+!6 = !DIMacro(type: DW_MACINFO_undef, line: 5, name: "BAR")