Index: lib/Driver/MinGWToolChain.cpp
===================================================================
--- lib/Driver/MinGWToolChain.cpp
+++ lib/Driver/MinGWToolChain.cpp
@@ -66,15 +66,20 @@
     : ToolChain(D, Triple, Args) {
   getProgramPaths().push_back(getDriver().getInstalledDir());

-  // On Windows if there is no sysroot we search for gcc on the PATH.
+  llvm::SmallVector<llvm::SmallString<32>, 2> Gccs;
+  Gccs.emplace_back(getTriple().getArchName());
+  Gccs[0] += "-w64-mingw32-gcc";
+  Gccs.emplace_back("mingw32-gcc");
+
+  for (StringRef CandidateGcc : Gccs)
+    if (llvm::ErrorOr<std::string> GPPName =
+          llvm::sys::findProgramByName(CandidateGcc))
+      Base = llvm::sys::path::parent_path(
+          llvm::sys::path::parent_path(GPPName.get()));
+
   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
+    Base = getDriver().SysRoot;
+
   if (!Base.size())
     Base = llvm::sys::path::parent_path(getDriver().getInstalledDir());