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
@@ -815,8 +815,10 @@
   HelpText<"Pass <arg> to the assembler">, MetaVarName<"<arg>">,
   Group<CompileOnly_Group>;
 def Xclang : Separate<["-"], "Xclang">,
-  HelpText<"Pass <arg> to the clang compiler">, MetaVarName<"<arg>">,
+  HelpText<"Pass <arg> to clang -cc1">, MetaVarName<"<arg>">,
   Flags<[NoXarchOption, CoreOption]>, Group<CompileOnly_Group>;
+def : Joined<["-"], "Xclang=">, Group<CompileOnly_Group>, Flags<[NoXarchOption, CoreOption]>, Alias<Xclang>,
+  HelpText<"Alias for -Xclang">, MetaVarName<"<arg>">;
 def Xcuda_fatbinary : Separate<["-"], "Xcuda-fatbinary">,
   HelpText<"Pass <arg> to fatbinary invocation">, MetaVarName<"<arg>">;
 def Xcuda_ptxas : Separate<["-"], "Xcuda-ptxas">,
diff --git a/clang/test/Driver/disable-llvm.c b/clang/test/Driver/disable-llvm.c
--- a/clang/test/Driver/disable-llvm.c
+++ b/clang/test/Driver/disable-llvm.c
@@ -1,6 +1,10 @@
 // We support a CC1 option for disabling LLVM's passes.
 // RUN: %clang -O2 -Xclang -disable-llvm-passes -### %s 2>&1 \
 // RUN:     | FileCheck --check-prefix=DISABLED %s
+
+// Try -Xclang=.
+// RUN: %clang -O2 -Xclang=-disable-llvm-passes -### %s 2>&1 \
+// RUN:     | FileCheck --check-prefix=DISABLED %s
 // DISABLED: -cc1
 // DISABLED-NOT: "-mllvm" "-disable-llvm-passes"
 // DISABLED: "-disable-llvm-passes"