Index: llvm/trunk/include/llvm/ObjectYAML/ELFYAML.h
===================================================================
--- llvm/trunk/include/llvm/ObjectYAML/ELFYAML.h
+++ llvm/trunk/include/llvm/ObjectYAML/ELFYAML.h
@@ -68,6 +68,7 @@
   ELF_ELFCLASS Class;
   ELF_ELFDATA Data;
   ELF_ELFOSABI OSABI;
+  llvm::yaml::Hex8 ABIVersion;
   ELF_ET Type;
   ELF_EM Machine;
   ELF_EF Flags;
Index: llvm/trunk/lib/ObjectYAML/ELFYAML.cpp
===================================================================
--- llvm/trunk/lib/ObjectYAML/ELFYAML.cpp
+++ llvm/trunk/lib/ObjectYAML/ELFYAML.cpp
@@ -753,6 +753,7 @@
   IO.mapRequired("Class", FileHdr.Class);
   IO.mapRequired("Data", FileHdr.Data);
   IO.mapOptional("OSABI", FileHdr.OSABI, ELFYAML::ELF_ELFOSABI(0));
+  IO.mapOptional("ABIVersion", FileHdr.ABIVersion, Hex8(0));
   IO.mapRequired("Type", FileHdr.Type);
   IO.mapRequired("Machine", FileHdr.Machine);
   IO.mapOptional("Flags", FileHdr.Flags, ELFYAML::ELF_EF(0));
Index: llvm/trunk/test/tools/yaml2obj/elf-abiversion.yaml
===================================================================
--- llvm/trunk/test/tools/yaml2obj/elf-abiversion.yaml
+++ llvm/trunk/test/tools/yaml2obj/elf-abiversion.yaml
@@ -0,0 +1,16 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-readobj -file-headers %t | FileCheck %s --check-prefix=FROMYAML
+# RUN: obj2yaml %t | FileCheck %s --check-prefix=TOYAML
+
+## Check we are able to parse/emit the ABI version with yaml2obj/obj2yaml.
+
+# FROMYAML: ABIVersion: 5
+# TOYAML:   ABIVersion: 0x05
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+  ABIVersion:      0x05
Index: llvm/trunk/tools/obj2yaml/elf2yaml.cpp
===================================================================
--- llvm/trunk/tools/obj2yaml/elf2yaml.cpp
+++ llvm/trunk/tools/obj2yaml/elf2yaml.cpp
@@ -114,6 +114,7 @@
   Y->Header.Class = ELFYAML::ELF_ELFCLASS(Obj.getHeader()->getFileClass());
   Y->Header.Data = ELFYAML::ELF_ELFDATA(Obj.getHeader()->getDataEncoding());
   Y->Header.OSABI = Obj.getHeader()->e_ident[ELF::EI_OSABI];
+  Y->Header.ABIVersion = Obj.getHeader()->e_ident[ELF::EI_ABIVERSION];
   Y->Header.Type = Obj.getHeader()->e_type;
   Y->Header.Machine = Obj.getHeader()->e_machine;
   Y->Header.Flags = Obj.getHeader()->e_flags;
Index: llvm/trunk/tools/yaml2obj/yaml2elf.cpp
===================================================================
--- llvm/trunk/tools/yaml2obj/yaml2elf.cpp
+++ llvm/trunk/tools/yaml2obj/yaml2elf.cpp
@@ -196,7 +196,7 @@
   Header.e_ident[EI_DATA] = IsLittleEndian ? ELFDATA2LSB : ELFDATA2MSB;
   Header.e_ident[EI_VERSION] = EV_CURRENT;
   Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
-  Header.e_ident[EI_ABIVERSION] = 0;
+  Header.e_ident[EI_ABIVERSION] = Doc.Header.ABIVersion;
   Header.e_type = Doc.Header.Type;
   Header.e_machine = Doc.Header.Machine;
   Header.e_version = EV_CURRENT;