diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -1990,7 +1990,8 @@
                              ArgStringList &CmdArgs) const {
   if (const Arg *A = Args.getLastArg(options::OPT_mtune_EQ)) {
     CmdArgs.push_back("-tune-cpu");
-    if (strcmp(A->getValue(), "native") == 0)
+    if (strcmp(A->getValue(), "native") == 0 ||
+        strcmp(A->getValue(), "auto") == 0)
       CmdArgs.push_back(Args.MakeArgString(llvm::sys::getHostCPUName()));
     else
       CmdArgs.push_back(A->getValue());
diff --git a/clang/test/Driver/ppc-cpus.c b/clang/test/Driver/ppc-cpus.c
--- a/clang/test/Driver/ppc-cpus.c
+++ b/clang/test/Driver/ppc-cpus.c
@@ -22,3 +22,5 @@
 
 // RUN: %clang -### -c --target=powerpc64 %s -mcpu=generic -mtune=pwr9 2>&1 | FileCheck %s --check-prefix=TUNE
 // TUNE: "-target-cpu" "ppc64" "-tune-cpu" "pwr9"
+// RUN: %clang -### -c --target=powerpc64 %s -mcpu=generic -mtune=auto 2>&1 | FileCheck %s --check-prefix=NO_AUTO
+// NO_AUTO-NOT: "-target-cpu" "ppc64" "-tune-cpu" "auto"