Index: include/clang/Driver/CLCompatOptions.td
===================================================================
--- include/clang/Driver/CLCompatOptions.td
+++ include/clang/Driver/CLCompatOptions.td
@@ -128,6 +128,10 @@
   HelpText<"Language standard to compile for">;
 def _SLASH_U : CLJoinedOrSeparate<"U">, HelpText<"Undefine macro">,
   MetaVarName<"<macro>">, Alias<U>;
+def _SLASH_validate_charset : CLFlag<"validate-charset">,
+  Alias<W_Joined>, AliasArgs<["invalid-source-encoding"]>;
+def _SLASH_validate_charset_ : CLFlag<"validate-charset-">,
+  Alias<W_Joined>, AliasArgs<["no-invalid-source-encoding"]>;
 def _SLASH_W0 : CLFlag<"W0">, HelpText<"Disable all warnings">, Alias<w>;
 def _SLASH_W1 : CLFlag<"W1">, HelpText<"Enable -Wall">, Alias<Wall>;
 def _SLASH_W2 : CLFlag<"W2">, HelpText<"Enable -Wall">, Alias<Wall>;
Index: test/Driver/cl-options.c
===================================================================
--- test/Driver/cl-options.c
+++ test/Driver/cl-options.c
@@ -192,6 +192,12 @@
 // RUN: %clang_cl /U mymacro -### -- %s 2>&1 | FileCheck -check-prefix=U %s
 // U: "-U" "mymacro"
 
+// RUN: %clang_cl /validate-charset -### -- %s 2>&1 | FileCheck -check-prefix=validate-charset %s
+// validate-charset: -Winvalid-source-encoding
+
+// RUN: %clang_cl /validate-charset- -### -- %s 2>&1 | FileCheck -check-prefix=validate-charset_ %s
+// validate-charset_: -Wno-invalid-source-encoding
+
 // RUN: %clang_cl /vd2 -### -- %s 2>&1 | FileCheck -check-prefix=VD2 %s
 // VD2: -vtordisp-mode=2