diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4156,7 +4156,7 @@
   HelpText<"Enable hexagon-qdsp6 backward compatibility">,
   MarshallingInfoFlag<LangOpts<"HexagonQdsp6Compat">>;
 def m64 : Flag<["-"], "m64">, Group<m_Group>, Flags<[NoXarchOption]>,
-  Visibility<[ClangOption, CLOption, DXCOption]>;
+  Visibility<[ClangOption, CLOption, DXCOption, FlangOption]>;
 def maix64 : Flag<["-"], "maix64">, Group<m_Group>, Flags<[NoXarchOption]>;
 def mx32 : Flag<["-"], "mx32">, Group<m_Group>, Flags<[NoXarchOption]>,
   Visibility<[ClangOption, CLOption, DXCOption]>;