Index: lib/Driver/ToolChains/MSVC.cpp
===================================================================
--- lib/Driver/ToolChains/MSVC.cpp
+++ lib/Driver/ToolChains/MSVC.cpp
@@ -752,6 +752,8 @@
     return "x64";
   case ArchType::arm:
     return "arm";
+  case ArchType::aarch64:
+    return "arm64";
   default:
     return "";
   }
@@ -769,6 +771,8 @@
     return "amd64";
   case ArchType::arm:
     return "arm";
+  case ArchType::aarch64:
+    return "arm64";
   default:
     return "";
   }
@@ -784,6 +788,8 @@
     return "amd64";
   case ArchType::arm:
     return "arm";
+  case ArchType::aarch64:
+    return "arm64";
   default:
     return "";
   }