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
@@ -1091,7 +1091,7 @@
 def dynamic : Flag<["-"], "dynamic">, Flags<[NoArgumentUnused]>;
 def d_Flag : Flag<["-"], "d">, Group<d_Group>;
 def d_Joined : Joined<["-"], "d">, Group<d_Group>;
-def emit_ast : Flag<["-"], "emit-ast">,
+def emit_ast : Flag<["-"], "emit-ast">, Flags<[CoreOption]>,
   HelpText<"Emit Clang AST files for source inputs">;
 def emit_llvm : Flag<["-"], "emit-llvm">, Flags<[CC1Option, FC1Option, FlangOption]>, Group<Action_Group>,
   HelpText<"Use the LLVM representation for assembler and object files">;
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -5625,7 +5625,8 @@
   // Determine what the derived output name should be.
   const char *NamedOutput;
 
-  if ((JA.getType() == types::TY_Object || JA.getType() == types::TY_LTO_BC) &&
+  if ((JA.getType() == types::TY_Object || JA.getType() == types::TY_LTO_BC ||
+       JA.getType() == types::TY_AST || JA.getType() == types::TY_Plist) &&
       C.getArgs().hasArg(options::OPT__SLASH_Fo, options::OPT__SLASH_o)) {
     // The /Fo or /o flag decides the object filename.
     StringRef Val =