diff --git a/lld/MachO/Config.h b/lld/MachO/Config.h
--- a/lld/MachO/Config.h
+++ b/lld/MachO/Config.h
@@ -12,6 +12,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/BinaryFormat/MachO.h"
+#include "llvm/TextAPI/MachO/Architecture.h"
 
 #include <vector>
 
@@ -26,6 +27,7 @@
   bool hasReexports = false;
   llvm::StringRef installName;
   llvm::StringRef outputFile;
+  llvm::MachO::Architecture arch;
   llvm::MachO::HeaderFileType outputType;
   std::vector<llvm::StringRef> searchPaths;
   llvm::DenseMap<llvm::StringRef, SymbolPriorityEntry> priorities;
diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -27,6 +27,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/BinaryFormat/MachO.h"
 #include "llvm/BinaryFormat/Magic.h"
+#include "llvm/Config/config.h"
 #include "llvm/Object/Archive.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/Option.h"
@@ -90,10 +91,16 @@
 }
 
 static TargetInfo *createTargetInfo(opt::InputArgList &args) {
-  StringRef s = args.getLastArgValue(OPT_arch, "x86_64");
-  if (s != "x86_64")
-    error("missing or unsupported -arch " + s);
-  return createX86_64TargetInfo();
+  StringRef arch = llvm::Triple(LLVM_DEFAULT_TARGET_TRIPLE).getArchName();
+  config->arch =
+      llvm::MachO::getArchitectureFromName(args.getLastArgValue(OPT_arch, arch));
+  switch (config->arch) {
+  case llvm::MachO::AK_x86_64:
+  case llvm::MachO::AK_x86_64h:
+    return createX86_64TargetInfo();
+  default:
+    fatal("missing or unsupported -arch " + args.getLastArgValue(OPT_arch));
+  }
 }
 
 static std::vector<StringRef> getSearchPaths(opt::InputArgList &args) {