diff -upNr a/llvm-3.1.src/tools/clang/lib/Driver/ToolChains.cpp b/llvm-3.1.src/tools/clang/lib/Driver/ToolChains.cpp
--- a/llvm-3.1.src/tools/clang/lib/Driver/ToolChains.cpp	2012-05-25 20:32:28.859469000 -0400
+++ b/llvm-3.1.src/tools/clang/lib/Driver/ToolChains.cpp	2012-05-25 20:33:15.988680000 -0400
@@ -2305,8 +2305,7 @@ void Linux::AddClangCXXStdlibIncludeArgs
     // Gentoo is weird and places its headers inside the GCC install, so if the
     // first attempt to find the headers fails, try this pattern.
     addLibStdCXXIncludePaths(InstallDir + "/include/g++-v4",
-                             (GCCInstallation.getTriple().str() +
-                              GCCInstallation.getMultiarchSuffix()),
+                             getDriver().DefaultTargetTriple,
                              DriverArgs, CC1Args);
   }
 }