Index: test/Driver/linux-header-search.cpp
===================================================================
--- test/Driver/linux-header-search.cpp	(revision 175152)
+++ test/Driver/linux-header-search.cpp	(working copy)
@@ -16,6 +16,21 @@
 // CHECK-UBUNTU-11-04: "-internal-externc-isystem" "[[SYSROOT]]/include"
 // CHECK-UBUNTU-11-04: "-internal-externc-isystem" "[[SYSROOT]]/usr/include"
 //
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
+// RUN:     -target x86_64-unknown-linux-gnu \
+// RUN:     --sysroot=%S/Inputs/ubuntu_13.04_multiarch_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-UBUNTU-13-04 %s
+// CHECK-UBUNTU-13-04: "{{[^"]*}}clang{{[^"]*}}" "-cc1"
+// CHECK-UBUNTU-13-04: "-isysroot" "[[SYSROOT:[^"]+]]"
+// CHECK-UBUNTU-13-04: "-internal-isystem" "[[SYSROOT]]/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7"
+// CHECK-UBUNTU-13-04: "-internal-isystem" "[[SYSROOT]]/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/backward"
+// CHECK-UBUNTU-13-04: "-internal-isystem" "[[SYSROOT]]/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/x86_64-linux-gnu/c++/4.7"
+// CHECK-UBUNTU-13-04: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
+// CHECK-UBUNTU-13-04: "-internal-isystem" "{{.*}}/lib{{(64|32)?}}/clang/{{[0-9]\.[0-9]}}/include"
+// CHECK-UBUNTU-13-04: "-internal-externc-isystem" "[[SYSROOT]]/usr/include/x86_64-linux-gnu"
+// CHECK-UBUNTU-13-04: "-internal-externc-isystem" "[[SYSROOT]]/include"
+// CHECK-UBUNTU-13-04: "-internal-externc-isystem" "[[SYSROOT]]/usr/include"
+//
 // Thoroughly exercise the Debian multiarch environment.
 // RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
 // RUN:     -target i686-linux-gnu \
Index: lib/Driver/ToolChains.h
===================================================================
--- lib/Driver/ToolChains.h	(revision 175152)
+++ lib/Driver/ToolChains.h	(working copy)
@@ -505,6 +505,10 @@
   std::vector<std::string> ExtraOpts;
 
 private:
+  static bool addLibStdCXXIncludePaths(Twine Base, Twine Suffix,
+                                       Twine TargetArchDir,
+                                       const ArgList &DriverArgs,
+                                       ArgStringList &CC1Args);
   static bool addLibStdCXXIncludePaths(Twine Base, Twine TargetArchDir,
                                        const ArgList &DriverArgs,
                                        ArgStringList &CC1Args);
Index: lib/Driver/ToolChains.cpp
===================================================================
--- lib/Driver/ToolChains.cpp	(revision 175152)
+++ lib/Driver/ToolChains.cpp	(working copy)
@@ -2592,7 +2592,7 @@
   addExternCSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/usr/include");
 }
 
-/// \brief Helper to add the thre variant paths for a libstdc++ installation.
+/// \brief Helper to add the three variant paths for a libstdc++ installation.
 /*static*/ bool Linux::addLibStdCXXIncludePaths(Twine Base, Twine TargetArchDir,
                                                 const ArgList &DriverArgs,
                                                 ArgStringList &CC1Args) {
@@ -2604,6 +2604,19 @@
   return true;
 }
 
+/// \brief Helper to add an extra variant path for a libstdc++ installation.
+/*static*/ bool Linux::addLibStdCXXIncludePaths(Twine Base, Twine Suffix,
+                                                Twine TargetArchDir,
+                                                const ArgList &DriverArgs,
+                                                ArgStringList &CC1Args) {
+  if (!addLibStdCXXIncludePaths(Base+Suffix, TargetArchDir,
+                                DriverArgs, CC1Args))
+    return false;
+
+  addSystemInclude(DriverArgs, CC1Args, Base + "/" + TargetArchDir + Suffix);
+  return true;
+}
+
 void Linux::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                          ArgStringList &CC1Args) const {
   if (DriverArgs.hasArg(options::OPT_nostdlibinc) ||
@@ -2631,8 +2644,13 @@
   StringRef Version = GCCInstallation.getVersion().Text;
   StringRef TripleStr = GCCInstallation.getTriple().str();
 
+  if (addLibStdCXXIncludePaths(LibDir.str() + "/../include", 
+                               "/c++/" + Version.str(),
+              (TripleStr + GCCInstallation.getMultiarchSuffix()),
+              DriverArgs, CC1Args))
+    return;
+
   const std::string IncludePathCandidates[] = {
-    LibDir.str() + "/../include/c++/" + Version.str(),
     // Gentoo is weird and places its headers inside the GCC install, so if the
     // first attempt to find the headers fails, try this pattern.
     InstallDir.str() + "/include/g++-v4",