diff --git a/clang/lib/Driver/ToolChains/Arch/PPC.h b/clang/lib/Driver/ToolChains/Arch/PPC.h
--- a/clang/lib/Driver/ToolChains/Arch/PPC.h
+++ b/clang/lib/Driver/ToolChains/Arch/PPC.h
@@ -37,6 +37,8 @@
 
 std::string getPPCTargetCPU(const llvm::opt::ArgList &Args,
                             const llvm::Triple &T);
+std::string getPPCTuneCPU(const llvm::opt::ArgList &Args,
+                          const llvm::Triple &T);
 const char *getPPCAsmModeForCPU(StringRef Name);
 ReadGOTPtrMode getPPCReadGOTPtrMode(const Driver &D, const llvm::Triple &Triple,
                                     const llvm::opt::ArgList &Args);
diff --git a/clang/lib/Driver/ToolChains/Arch/PPC.cpp b/clang/lib/Driver/ToolChains/Arch/PPC.cpp
--- a/clang/lib/Driver/ToolChains/Arch/PPC.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/PPC.cpp
@@ -34,53 +34,60 @@
     return "ppc";
 }
 
-/// getPPCTargetCPU - Get the (LLVM) name of the PowerPC cpu we are targeting.
-std::string ppc::getPPCTargetCPU(const ArgList &Args, const llvm::Triple &T) {
-  if (Arg *A = Args.getLastArg(clang::driver::options::OPT_mcpu_EQ)) {
-    StringRef CPUName = A->getValue();
-
-    // Clang/LLVM does not actually support code generation
-    // for the 405 CPU. However, there are uses of this CPU ID
-    // in projects that previously used GCC and rely on Clang
-    // accepting it. Clang has always ignored it and passed the
-    // generic CPU ID to the back end.
-    if (CPUName == "generic" || CPUName == "405")
+static std::string normalizeCPUName(StringRef CPUName, const llvm::Triple &T) {
+  // Clang/LLVM does not actually support code generation
+  // for the 405 CPU. However, there are uses of this CPU ID
+  // in projects that previously used GCC and rely on Clang
+  // accepting it. Clang has always ignored it and passed the
+  // generic CPU ID to the back end.
+  if (CPUName == "generic" || CPUName == "405")
+    return getPPCGenericTargetCPU(T);
+
+  if (CPUName == "native") {
+    std::string CPU = std::string(llvm::sys::getHostCPUName());
+    if (!CPU.empty() && CPU != "generic")
+      return CPU;
+    else
       return getPPCGenericTargetCPU(T);
+  }
 
-    if (CPUName == "native") {
-      std::string CPU = std::string(llvm::sys::getHostCPUName());
-      if (!CPU.empty() && CPU != "generic")
-        return CPU;
-      else
-        return getPPCGenericTargetCPU(T);
-    }
+  return llvm::StringSwitch<const char *>(CPUName)
+      .Case("common", "generic")
+      .Case("440fp", "440")
+      .Case("630", "pwr3")
+      .Case("G3", "g3")
+      .Case("G4", "g4")
+      .Case("G4+", "g4+")
+      .Case("8548", "e500")
+      .Case("G5", "g5")
+      .Case("power3", "pwr3")
+      .Case("power4", "pwr4")
+      .Case("power5", "pwr5")
+      .Case("power5x", "pwr5x")
+      .Case("power6", "pwr6")
+      .Case("power6x", "pwr6x")
+      .Case("power7", "pwr7")
+      .Case("power8", "pwr8")
+      .Case("power9", "pwr9")
+      .Case("power10", "pwr10")
+      .Case("future", "future")
+      .Case("powerpc", "ppc")
+      .Case("powerpc64", "ppc64")
+      .Case("powerpc64le", "ppc64le")
+      .Default(CPUName.data());
+}
 
-    return llvm::StringSwitch<const char *>(CPUName)
-        .Case("common", "generic")
-        .Case("440fp", "440")
-        .Case("630", "pwr3")
-        .Case("G3", "g3")
-        .Case("G4", "g4")
-        .Case("G4+", "g4+")
-        .Case("8548", "e500")
-        .Case("G5", "g5")
-        .Case("power3", "pwr3")
-        .Case("power4", "pwr4")
-        .Case("power5", "pwr5")
-        .Case("power5x", "pwr5x")
-        .Case("power6", "pwr6")
-        .Case("power6x", "pwr6x")
-        .Case("power7", "pwr7")
-        .Case("power8", "pwr8")
-        .Case("power9", "pwr9")
-        .Case("power10", "pwr10")
-        .Case("future", "future")
-        .Case("powerpc", "ppc")
-        .Case("powerpc64", "ppc64")
-        .Case("powerpc64le", "ppc64le")
-        .Default(CPUName.data());
-  }
+/// Get the (LLVM) name of the PowerPC cpu we are tuning for.
+std::string ppc::getPPCTuneCPU(const ArgList &Args, const llvm::Triple &T) {
+  if (Arg *A = Args.getLastArg(clang::driver::options::OPT_mtune_EQ))
+    return normalizeCPUName(A->getValue(), T);
+  return getPPCGenericTargetCPU(T);
+}
 
+/// Get the (LLVM) name of the PowerPC cpu we are targeting.
+std::string ppc::getPPCTargetCPU(const ArgList &Args, const llvm::Triple &T) {
+  if (Arg *A = Args.getLastArg(clang::driver::options::OPT_mcpu_EQ))
+    return normalizeCPUName(A->getValue(), T);
   return getPPCGenericTargetCPU(T);
 }
 
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
@@ -1992,17 +1992,15 @@
 
 void Clang::AddPPCTargetArgs(const ArgList &Args,
                              ArgStringList &CmdArgs) const {
+  const llvm::Triple &T = getToolChain().getTriple();
   if (const Arg *A = Args.getLastArg(options::OPT_mtune_EQ)) {
     CmdArgs.push_back("-tune-cpu");
-    if (strcmp(A->getValue(), "native") == 0)
-      CmdArgs.push_back(Args.MakeArgString(llvm::sys::getHostCPUName()));
-    else
-      CmdArgs.push_back(A->getValue());
+    std::string CPU = ppc::getPPCTuneCPU(Args, T);
+    CmdArgs.push_back(Args.MakeArgString(CPU));
   }
 
   // Select the ABI to use.
   const char *ABIName = nullptr;
-  const llvm::Triple &T = getToolChain().getTriple();
   if (T.isOSBinFormatELF()) {
     switch (getToolChain().getArch()) {
     case llvm::Triple::ppc64: {
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
@@ -31,6 +31,8 @@
 
 // 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=powerpc64le %s -mcpu=power9 -mtune=power10 2>&1 | FileCheck %s --check-prefix=TUNE-LONG
+// TUNE-LONG: "-target-cpu" "pwr9" "-tune-cpu" "pwr10"
 
 /// Test mcpu options that are equivalent to "generic"
 // RUN: %clang -### -c -target powerpc64 %s -mcpu=generic 2>&1 | FileCheck %s --check-prefix=GENERIC