Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -4690,6 +4690,8 @@
 
 def _SLASH_arch : CLCompileJoined<"arch:">,
   HelpText<"Set architecture for code generation">;
+def _SLASH_tune : CLCompileJoined<"tune:">,
+  HelpText<"Set CPU for optimization without affecting instruction set">;
 
 def _SLASH_M_Group : OptionGroup<"</M group>">, Group<cl_compile_Group>;
 def _SLASH_volatile_Group : OptionGroup<"</volatile group>">,
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -2080,8 +2080,9 @@
   if (!Args.hasArg(clang::driver::options::OPT_march_EQ))
     TuneCPU = "generic";
 
-  // Override based on -mtune.
-  if (const Arg *A = Args.getLastArg(clang::driver::options::OPT_mtune_EQ)) {
+  // Override based on -mtune or /tune:
+  if (const Arg *A = Args.getLastArg(clang::driver::options::OPT_mtune_EQ,
+                                     clang::driver::options::OPT__SLASH_tune)) {
     StringRef Name = A->getValue();
 
     if (Name == "native") {
Index: clang/test/Driver/cl-x86-flags.c
===================================================================
--- clang/test/Driver/cl-x86-flags.c
+++ clang/test/Driver/cl-x86-flags.c
@@ -128,5 +128,9 @@
 // RUN: %clang_cl -m64 -arch:avx512 --target=i386-pc-windows -### -- 2>&1 %s | FileCheck -check-prefix=avx51264 %s
 // avx51264: argument unused during compilation
 
+// RUN: %clang_cl -m64 -arch:AVX -tune:haswell --target=x86_64-pc-windows -### -- 2>&1 %s | FileCheck -check-prefix=tune %s
+// tune: "-target-cpu" "sandybridge"
+// tune-SAME: "-tune-cpu" "haswell"
+
 void f() {
 }