diff --git a/include/clang/Driver/ToolChain.h b/include/clang/Driver/ToolChain.h
index cc8d438..501e833 100644
--- a/include/clang/Driver/ToolChain.h
+++ b/include/clang/Driver/ToolChain.h
@@ -53,9 +53,9 @@
   const Driver &getDriver() const;
   const llvm::Triple &getTriple() const { return Triple; }
 
-  std::string getArchName() const { return Triple.getArchName(); }
-  std::string getPlatform() const { return Triple.getVendorName(); }
-  std::string getOS() const { return Triple.getOSName(); }
+  llvm::StringRef getArchName() const { return Triple.getArchName(); }
+  llvm::StringRef getPlatform() const { return Triple.getVendorName(); }
+  llvm::StringRef getOS() const { return Triple.getOSName(); }
 
   std::string getTripleString() const {
     return Triple.getTriple();
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 2e7435f..2354bd4 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -512,7 +512,7 @@
   // Select the default CPU if none was given (or detection failed).
   if (!CPUName) {
     // FIXME: Need target hooks.
-    if (memcmp(getToolChain().getOS().c_str(), "darwin", 6) == 0) {
+    if (getToolChain().getOS().startswith("darwin")) {
       if (getToolChain().getArchName() == "x86_64")
         CPUName = "core2";
       else if (getToolChain().getArchName() == "i386")