diff --git a/llvm/include/llvm/ObjectYAML/DWARFYAML.h b/llvm/include/llvm/ObjectYAML/DWARFYAML.h
--- a/llvm/include/llvm/ObjectYAML/DWARFYAML.h
+++ b/llvm/include/llvm/ObjectYAML/DWARFYAML.h
@@ -83,7 +83,7 @@
 /// Class that describes a single range list inside the .debug_ranges section.
 struct Ranges {
   Optional<llvm::yaml::Hex64> Offset;
-  llvm::yaml::Hex8 AddrSize;
+  Optional<llvm::yaml::Hex8> AddrSize;
   std::vector<RangeEntry> Entries;
 };
 
@@ -162,6 +162,7 @@
 
 struct Data {
   bool IsLittleEndian;
+  bool Is64bit;
   std::vector<Abbrev> AbbrevDecls;
   std::vector<StringRef> DebugStrings;
   std::vector<ARange> ARanges;
diff --git a/llvm/lib/ObjectYAML/DWARFEmitter.cpp b/llvm/lib/ObjectYAML/DWARFEmitter.cpp
--- a/llvm/lib/ObjectYAML/DWARFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/DWARFEmitter.cpp
@@ -148,13 +148,19 @@
                                    Twine::utohexstr(CurrOffset) + ")");
     if (DebugRanges.Offset)
       ZeroFillBytes(OS, *DebugRanges.Offset - CurrOffset);
+
+    uint8_t AddrSize;
+    if (DebugRanges.AddrSize)
+      AddrSize = *DebugRanges.AddrSize;
+    else
+      AddrSize = DI.Is64bit ? 8 : 4;
     for (auto Entry : DebugRanges.Entries) {
-      writeVariableSizedInteger(Entry.LowOffset, DebugRanges.AddrSize, OS,
+      writeVariableSizedInteger(Entry.LowOffset, AddrSize, OS,
                                 DI.IsLittleEndian);
-      writeVariableSizedInteger(Entry.HighOffset, DebugRanges.AddrSize, OS,
+      writeVariableSizedInteger(Entry.HighOffset, AddrSize, OS,
                                 DI.IsLittleEndian);
     }
-    ZeroFillBytes(OS, DebugRanges.AddrSize * 2);
+    ZeroFillBytes(OS, AddrSize * 2);
     ++EntryIndex;
   }
 
diff --git a/llvm/lib/ObjectYAML/DWARFYAML.cpp b/llvm/lib/ObjectYAML/DWARFYAML.cpp
--- a/llvm/lib/ObjectYAML/DWARFYAML.cpp
+++ b/llvm/lib/ObjectYAML/DWARFYAML.cpp
@@ -97,7 +97,7 @@
 void MappingTraits<DWARFYAML::Ranges>::mapping(IO &IO,
                                                DWARFYAML::Ranges &DebugRanges) {
   IO.mapOptional("Offset", DebugRanges.Offset);
-  IO.mapRequired("AddrSize", DebugRanges.AddrSize);
+  IO.mapOptional("AddrSize", DebugRanges.AddrSize);
   IO.mapRequired("Entries", DebugRanges.Entries);
 }
 
diff --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -1655,9 +1655,12 @@
   IO.mapOptional("Symbols", Object.Symbols);
   IO.mapOptional("DynamicSymbols", Object.DynamicSymbols);
   IO.mapOptional("DWARF", Object.DWARF);
-  if (Object.DWARF)
+  if (Object.DWARF) {
     Object.DWARF->IsLittleEndian =
         Object.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
+    Object.DWARF->Is64bit =
+        Object.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
+  }
   IO.setContext(nullptr);
 }
 
diff --git a/llvm/lib/ObjectYAML/MachOYAML.cpp b/llvm/lib/ObjectYAML/MachOYAML.cpp
--- a/llvm/lib/ObjectYAML/MachOYAML.cpp
+++ b/llvm/lib/ObjectYAML/MachOYAML.cpp
@@ -107,6 +107,8 @@
   Object.DWARF.IsLittleEndian = Object.IsLittleEndian;
 
   IO.mapRequired("FileHeader", Object.Header);
+  Object.DWARF.Is64bit = Object.Header.magic == MachO::MH_MAGIC_64 ||
+                         Object.Header.magic == MachO::MH_CIGAM_64;
   IO.mapOptional("LoadCommands", Object.LoadCommands);
   if(!Object.LinkEdit.isEmpty() || !IO.outputting())
     IO.mapOptional("LinkEditData", Object.LinkEdit);
diff --git a/llvm/test/tools/obj2yaml/macho-DWARF-debug-ranges.yaml b/llvm/test/tools/obj2yaml/macho-DWARF-debug-ranges.yaml
--- a/llvm/test/tools/obj2yaml/macho-DWARF-debug-ranges.yaml
+++ b/llvm/test/tools/obj2yaml/macho-DWARF-debug-ranges.yaml
@@ -203,7 +203,6 @@
           Form:            DW_FORM_addr
   debug_ranges:
     - Offset:          0x00000000
-      AddrSize:        0x08
       Entries:
         - LowOffset:       0x0000000000000000
           HighOffset:      0x0000000000000020
diff --git a/llvm/test/tools/yaml2obj/ELF/DWARF/debug-ranges.yaml b/llvm/test/tools/yaml2obj/ELF/DWARF/debug-ranges.yaml
--- a/llvm/test/tools/yaml2obj/ELF/DWARF/debug-ranges.yaml
+++ b/llvm/test/tools/yaml2obj/ELF/DWARF/debug-ranges.yaml
@@ -84,8 +84,7 @@
           HighOffset: 0x00000010
         - LowOffset:  0x00000000
           HighOffset: 0x00000000
-    - AddrSize: 0x08
-      Entries:
+    - Entries:
         - LowOffset:  0x0000000000000010
           HighOffset: 0x0000000000000020
         - LowOffset:  0x0000000000000030
@@ -207,8 +206,7 @@
     Size: 0x10
 DWARF:
   debug_ranges:
-    - AddrSize: 0x08
-      Entries:
+    - Entries:
         - LowOffset:  0x0000000000000001
           HighOffset: 0x0000000000000002
 
@@ -229,8 +227,7 @@
     Content: "00"
 DWARF:
   debug_ranges:
-    - AddrSize: 0x08
-      Entries:
+    - Entries:
         - LowOffset:  0x0000000000000001
           HighOffset: 0x0000000000000002
 
@@ -290,8 +287,7 @@
     Type:         SHT_STRTAB
 DWARF:
   debug_ranges:
-    - AddrSize: 0x08
-      Entries:
+    - Entries:
         - LowOffset:  0x0000000000000001
           HighOffset: 0x0000000000000002
 
@@ -345,17 +341,14 @@
   Machine: EM_X86_64
 DWARF:
   debug_ranges:
-    - AddrSize: 0x08
-      Entries:
+    - Entries:
         - LowOffset:  0x01
           HighOffset: 0x02
     - Offset:   0x21  ## There are 0x20 bytes before this entry.
-      AddrSize: 0x08
       Entries:
         - LowOffset:  0x01
           HighOffset: 0x02
     - Offset:   0x41  ## There are 0x41 bytes before this entry.
-      AddrSize: 0x08
       Entries:
         - LowOffset:  0x01
           HighOffset: 0x02
@@ -375,12 +368,10 @@
   Machine: EM_X86_64
 DWARF:
   debug_ranges:
-    - AddrSize: 0x08
-      Entries:
+    - Entries:
         - LowOffset:  0x01
           HighOffset: 0x02
     - Offset:   0x1F ## Must be greater than or equal to 0x20.
-      AddrSize: 0x08
       Entries:
         - LowOffset:  0x01
           HighOffset: 0x02