Index: llvm/trunk/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
===================================================================
--- llvm/trunk/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
+++ llvm/trunk/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
@@ -76,6 +76,7 @@
       .Case("i386", IMAGE_FILE_MACHINE_I386)
       .Case("i386:x86-64", IMAGE_FILE_MACHINE_AMD64)
       .Case("arm", IMAGE_FILE_MACHINE_ARMNT)
+      .Case("arm64", IMAGE_FILE_MACHINE_ARM64)
       .Default(IMAGE_FILE_MACHINE_UNKNOWN);
 }
 
Index: llvm/trunk/test/DllTool/coff-exports.def
===================================================================
--- llvm/trunk/test/DllTool/coff-exports.def
+++ llvm/trunk/test/DllTool/coff-exports.def
@@ -1,5 +1,7 @@
 ; RUN: llvm-dlltool -m i386:x86-64 --input-def %s --output-lib %t.a
 ; RUN: llvm-readobj -coff-exports %t.a | FileCheck %s
+; RUN: llvm-dlltool -m arm64 --input-def %s --output-lib %t.a
+; RUN: llvm-readobj -coff-exports %t.a | FileCheck %s
 
 LIBRARY test.dll
 EXPORTS