1 files changed, 12 insertions, 0 deletions
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index 3d4f12cb86..6d31e46204 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -56,6 +56,10 @@ using namespace clang;
 /// \brief Utility function to add a system include directory to CC1 arguments.
 static void addSystemInclude(const ArgList &DriverArgs, ArgStringList &CC1Args,
                              const Twine &Path) {
+  // Prune out non-existent directories to minimize the number of flags.
+  if (!llvm::sys::fs::exists(Path))
+    return;
+
   CC1Args.push_back("-internal-isystem");
   CC1Args.push_back(DriverArgs.MakeArgString(Path));
 }
@@ -70,6 +74,10 @@ static void addSystemInclude(const ArgList &DriverArgs, ArgStringList &CC1Args,
 /// classification.
 static void addExternCSystemInclude(const ArgList &DriverArgs,
                                     ArgStringList &CC1Args, const Twine &Path) {
+  // Prune out non-existent directories to minimize the number of flags.
+  if (!llvm::sys::fs::exists(Path))
+    return;
+
   CC1Args.push_back("-internal-externc-isystem");
   CC1Args.push_back(DriverArgs.MakeArgString(Path));
 }
@@ -80,6 +88,10 @@ static void addSystemIncludes(const ArgList &DriverArgs,
                               ArrayRef<StringRef> Paths) {
   for (ArrayRef<StringRef>::iterator I = Paths.begin(), E = Paths.end();
        I != E; ++I) {
+    // Prune out non-existent directories to minimize the number of flags.
+    if (!llvm::sys::fs::exists(*I))
+      continue;
+
     CC1Args.push_back("-internal-isystem");
     CC1Args.push_back(DriverArgs.MakeArgString(*I));
   }