Index: lib/Driver/MinGWToolChain.cpp
===================================================================
--- lib/Driver/MinGWToolChain.cpp
+++ lib/Driver/MinGWToolChain.cpp
@@ -68,21 +68,16 @@
 
 // In Windows there aren't any standard install locations, we search
 // for gcc on the PATH. In Linux the base is always /usr.
-#ifdef LLVM_ON_WIN32
   if (getDriver().SysRoot.size())
     Base = getDriver().SysRoot;
+#ifdef LLVM_ON_WIN32
   else if (llvm::ErrorOr<std::string> GPPName =
                llvm::sys::findProgramByName("gcc"))
     Base = llvm::sys::path::parent_path(
         llvm::sys::path::parent_path(GPPName.get()));
+#endif
   else
     Base = llvm::sys::path::parent_path(getDriver().getInstalledDir());
-#else
-  if (getDriver().SysRoot.size())
-    Base = getDriver().SysRoot;
-  else
-    Base = "/usr";
-#endif
 
   Base += llvm::sys::path::get_separator();
   findGccLibDir();