Index: test/tools/llvm-objcopy/ELF/binary-input-with-arch.test
===================================================================
--- test/tools/llvm-objcopy/ELF/binary-input-with-arch.test
+++ test/tools/llvm-objcopy/ELF/binary-input-with-arch.test
@@ -2,19 +2,25 @@
 # Preserve input to verify it is not modified.
 # RUN: cp %t.x-txt %t-copy.txt
 # RUN: llvm-objcopy -I binary -B i386 -O elf64-x86-64 %t.x-txt %t.o
-# RUN: llvm-readobj --file-headers %t.o | FileCheck %s
+# RUN: llvm-readobj --file-headers %t.o | FileCheck %s --check-prefixes=CHECK,SYSV
 # RUN: cmp %t.x-txt %t-copy.txt
 
 # Many uses of objcopy use no spaces in the flags, make sure that also works.
 # RUN: llvm-objcopy -Ibinary -Bi386 -Oelf64-x86-64 %t.x-txt %t-no-spaces.o
 # RUN: cmp %t.o %t-no-spaces.o
 
+# elf64-x86-64-freebsd sets the OS/ABI field.
+# RUN: llvm-objcopy -I binary -B i386 -O elf64-x86-64-freebsd %t.x-txt %t.freebsd.o
+# RUN: llvm-readobj --file-headers %t.freebsd.o | FileCheck %s --check-prefixes=CHECK,FREEBSD
+
 # CHECK:      Format: ELF64-x86-64
 # CHECK-NEXT: Arch: x86_64
 # CHECK-NEXT: AddressSize: 64bit
 
 # CHECK: Class: 64-bit
 # CHECK: DataEncoding: LittleEndian
+# SYSV:    OS/ABI: SystemV
+# FREEBSD: OS/ABI: FreeBSD
 # CHECK: Machine: EM_X86_64
 # CHECK: HeaderSize: 64
 # CHECK: SectionHeaderEntrySize: 64
Index: test/tools/llvm-objcopy/ELF/cross-arch-headers.test
===================================================================
--- test/tools/llvm-objcopy/ELF/cross-arch-headers.test
+++ test/tools/llvm-objcopy/ELF/cross-arch-headers.test
@@ -1,19 +1,25 @@
 # RUN: yaml2obj %s > %t.o
 
 # RUN: llvm-objcopy %t.o -O elf32-i386 %t.elf32_i386.o
-# RUN: llvm-readobj --file-headers %t.elf32_i386.o | FileCheck %s --check-prefixes=CHECK,I386,32
+# RUN: llvm-readobj --file-headers %t.elf32_i386.o | FileCheck %s --check-prefixes=CHECK,I386,32,SYSV
 
 # RUN: llvm-objcopy %t.o -O elf32-powerpcle %t.elf32_ppcle.o
-# RUN: llvm-readobj --file-headers %t.elf32_ppcle.o | FileCheck %s --check-prefixes=CHECK,PPC,32
+# RUN: llvm-readobj --file-headers %t.elf32_ppcle.o | FileCheck %s --check-prefixes=CHECK,PPC,32,SYSV
 
 # RUN: llvm-objcopy %t.o -O elf32-x86-64 %t.elf32_x86_64.o
-# RUN: llvm-readobj --file-headers %t.elf32_x86_64.o | FileCheck %s --check-prefixes=CHECK,X86-64,32
+# RUN: llvm-readobj --file-headers %t.elf32_x86_64.o | FileCheck %s --check-prefixes=CHECK,X86-64,32,SYSV
 
 # RUN: llvm-objcopy %t.o -O elf64-powerpcle %t.elf64_ppcle.o
-# RUN: llvm-readobj --file-headers %t.elf64_ppcle.o | FileCheck %s --check-prefixes=CHECK,PPC64,64
+# RUN: llvm-readobj --file-headers %t.elf64_ppcle.o | FileCheck %s --check-prefixes=CHECK,PPC64,64,SYSV
 
 # RUN: llvm-objcopy %t.o -O elf64-x86-64 %t.elf64_x86_64.o
-# RUN: llvm-readobj --file-headers %t.elf64_x86_64.o | FileCheck %s --check-prefixes=CHECK,X86-64,64
+# RUN: llvm-readobj --file-headers %t.elf64_x86_64.o | FileCheck %s --check-prefixes=CHECK,X86-64,64,SYSV
+
+# RUN: llvm-objcopy %t.o -O elf64-x86-64-freebsd %t.elf64_x86_64_freebsd.o
+# RUN: llvm-readobj --file-headers %t.elf64_x86_64_freebsd.o | FileCheck %s --check-prefixes=CHECK,X86-64,64,FREEBSD
+
+# RUN: llvm-objcopy %t.o -O elf32-i386-freebsd %t.elf32_i386_freebsd.o
+# RUN: llvm-readobj --file-headers %t.elf32_i386_freebsd.o | FileCheck %s --check-prefixes=CHECK,I386,32,FREEBSD
 
 !ELF
 FileHeader:
@@ -21,6 +27,7 @@
   Data:            ELFDATA2LSB
   Type:            ET_EXEC
   Machine:         EM_386
+  OSABI:           ELFOSABI_STANDALONE # Arbitrary non-zero value.
 Sections:
   - Name:            .text
     Type:            SHT_PROGBITS
@@ -59,6 +66,9 @@
 # 64:     Class: 64-bit
 # CHECK:  DataEncoding: LittleEndian
 
+# SYSV:    OS/ABI: SystemV (0x0)
+# FREEBSD: OS/ABI: FreeBSD (0x9)
+
 # I386:   Machine: EM_386
 # PPC:    Machine: EM_PPC
 # PPC64:  Machine: EM_PPC64
Index: tools/llvm-objcopy/CopyConfig.h
===================================================================
--- tools/llvm-objcopy/CopyConfig.h
+++ tools/llvm-objcopy/CopyConfig.h
@@ -30,6 +30,7 @@
 // ELF file.
 struct MachineInfo {
   uint16_t EMachine;
+  uint8_t OSABI;
   bool Is64Bit;
   bool IsLittleEndian;
 };
Index: tools/llvm-objcopy/CopyConfig.cpp
===================================================================
--- tools/llvm-objcopy/CopyConfig.cpp
+++ tools/llvm-objcopy/CopyConfig.cpp
@@ -282,14 +282,14 @@
 }
 
 static const StringMap<MachineInfo> ArchMap{
-    // Name, {EMachine, 64bit, LittleEndian}
-    {"aarch64", {ELF::EM_AARCH64, true, true}},
-    {"arm", {ELF::EM_ARM, false, true}},
-    {"i386", {ELF::EM_386, false, true}},
-    {"i386:x86-64", {ELF::EM_X86_64, true, true}},
-    {"powerpc:common64", {ELF::EM_PPC64, true, true}},
-    {"sparc", {ELF::EM_SPARC, false, true}},
-    {"x86-64", {ELF::EM_X86_64, true, true}},
+    // Name, {EMachine, OS/ABI, 64bit, LittleEndian}
+    {"aarch64", {ELF::EM_AARCH64, ELF::ELFOSABI_NONE, true, true}},
+    {"arm", {ELF::EM_ARM, ELF::ELFOSABI_NONE, false, true}},
+    {"i386", {ELF::EM_386, ELF::ELFOSABI_NONE, false, true}},
+    {"i386:x86-64", {ELF::EM_X86_64, ELF::ELFOSABI_NONE, true, true}},
+    {"powerpc:common64", {ELF::EM_PPC64, ELF::ELFOSABI_NONE, true, true}},
+    {"sparc", {ELF::EM_SPARC, ELF::ELFOSABI_NONE, false, true}},
+    {"x86-64", {ELF::EM_X86_64, ELF::ELFOSABI_NONE, true, true}},
 };
 
 static Expected<const MachineInfo &> getMachineInfo(StringRef Arch) {
@@ -301,12 +301,15 @@
 }
 
 static const StringMap<MachineInfo> OutputFormatMap{
-    // Name, {EMachine, 64bit, LittleEndian}
-    {"elf32-i386", {ELF::EM_386, false, true}},
-    {"elf32-powerpcle", {ELF::EM_PPC, false, true}},
-    {"elf32-x86-64", {ELF::EM_X86_64, false, true}},
-    {"elf64-powerpcle", {ELF::EM_PPC64, true, true}},
-    {"elf64-x86-64", {ELF::EM_X86_64, true, true}},
+    // Name, {EMachine, OSABI, 64bit, LittleEndian}
+    {"elf32-i386", {ELF::EM_386, ELF::ELFOSABI_NONE, false, true}},
+    {"elf32-i386-freebsd", {ELF::EM_386, ELF::ELFOSABI_FREEBSD, false, true}},
+    {"elf32-powerpcle", {ELF::EM_PPC, ELF::ELFOSABI_NONE, false, true}},
+    {"elf32-x86-64", {ELF::EM_X86_64, ELF::ELFOSABI_NONE, false, true}},
+    {"elf64-powerpcle", {ELF::EM_PPC64, ELF::ELFOSABI_NONE, true, true}},
+    {"elf64-x86-64", {ELF::EM_X86_64, ELF::ELFOSABI_NONE, true, true}},
+    {"elf64-x86-64-freebsd",
+     {ELF::EM_X86_64, ELF::ELFOSABI_FREEBSD, true, true}},
 };
 
 static Expected<const MachineInfo &>
Index: tools/llvm-objcopy/ELF/ELFObjcopy.cpp
===================================================================
--- tools/llvm-objcopy/ELF/ELFObjcopy.cpp
+++ tools/llvm-objcopy/ELF/ELFObjcopy.cpp
@@ -224,8 +224,10 @@
   };
   if (Error E = DWOFile->removeSections(OnlyKeepDWOPred))
     return E;
-  if (Config.OutputArch)
+  if (Config.OutputArch) {
     DWOFile->Machine = Config.OutputArch.getValue().EMachine;
+    DWOFile->OSABI = Config.OutputArch.getValue().OSABI;
+  }
   FileBuffer FB(File);
   auto Writer = createWriter(Config, *DWOFile, FB, OutputElfType);
   if (Error E = Writer->finalize())
@@ -311,8 +313,10 @@
             splitDWOToFile(Config, Reader, Config.SplitDWO, OutputElfType))
       return E;
 
-  if (Config.OutputArch)
+  if (Config.OutputArch) {
     Obj.Machine = Config.OutputArch.getValue().EMachine;
+    Obj.OSABI = Config.OutputArch.getValue().OSABI;
+  }
 
   // TODO: update or remove symbols only if there is an option that affects
   // them.