Index: lib/Driver/Driver.cpp
===================================================================
--- lib/Driver/Driver.cpp
+++ lib/Driver/Driver.cpp
@@ -81,6 +81,7 @@
 #include <utility>
 #if LLVM_ON_UNIX
 #include <unistd.h> // getpid
+#include <sysexits.h> // EX_IOERR
 #endif
 
 using namespace clang::driver;
@@ -1388,8 +1389,9 @@
 
   // Otherwise, remove result files and print extra information about abnormal
   // failures.
+  int Res = 0;
   for (const auto &CmdPair : FailingCommands) {
-    int Res = CmdPair.first;
+    int CommandRes = CmdPair.first;
     const Command *FailingCommand = CmdPair.second;
 
     // Remove result files if we're not saving temps.
@@ -1398,10 +1400,19 @@
       C.CleanupFileMap(C.getResultFiles(), JA, true);
 
       // Failure result files are valid unless we crashed.
-      if (Res < 0)
+      if (CommandRes < 0)
         C.CleanupFileMap(C.getFailureResultFiles(), JA, true);
     }
 
+#if LLVM_ON_UNIX
+    // llvm/lib/Support/Unix/Signals.inc will exit with a special return code
+    // for SIGPIPE. Do not print diagnostics for this case.
+    if (CommandRes == EX_IOERR) {
+      Res = CommandRes;
+      continue;
+    }
+#endif
+
     // Print extra information about abnormal failures, if possible.
     //
     // This is ad-hoc, but we don't want to be excessively noisy. If the result
@@ -1411,17 +1422,17 @@
     // diagnostics, so always print the diagnostic there.
     const Tool &FailingTool = FailingCommand->getCreator();
 
-    if (!FailingCommand->getCreator().hasGoodDiagnostics() || Res != 1) {
+    if (!FailingCommand->getCreator().hasGoodDiagnostics() || CommandRes != 1) {
       // FIXME: See FIXME above regarding result code interpretation.
-      if (Res < 0)
+      if (CommandRes < 0)
         Diag(clang::diag::err_drv_command_signalled)
             << FailingTool.getShortName();
       else
-        Diag(clang::diag::err_drv_command_failed) << FailingTool.getShortName()
-                                                  << Res;
+        Diag(clang::diag::err_drv_command_failed)
+            << FailingTool.getShortName() << CommandRes;
     }
   }
-  return 0;
+  return Res;
 }
 
 void Driver::PrintHelp(bool ShowHidden) const {