Index: clang/include/clang/Driver/Driver.h
===================================================================
--- clang/include/clang/Driver/Driver.h
+++ clang/include/clang/Driver/Driver.h
@@ -51,7 +51,8 @@
   LTOK_None,
   LTOK_Full,
   LTOK_Thin,
-  LTOK_Unknown
+  LTOK_Unknown,
+  LTOK_Ignored
 };
 
 /// Driver - Encapsulate logic for constructing compilation processes
Index: clang/lib/Driver/Driver.cpp
===================================================================
--- clang/lib/Driver/Driver.cpp
+++ clang/lib/Driver/Driver.cpp
@@ -610,9 +610,12 @@
   LTOMode = llvm::StringSwitch<LTOKind>(LTOName)
                 .Case("full", LTOK_Full)
                 .Case("thin", LTOK_Thin)
+                .Case("auto", LTOK_Ignored)
+                .Case("jobserver", LTOK_Ignored)
                 .Default(LTOK_Unknown);
 
   if (LTOMode == LTOK_Unknown) {
+    // FIXME: check if argument is a number, then ignore, or handle it
     assert(A);
     Diag(diag::err_drv_unsupported_option_argument) << A->getOption().getName()
                                                     << A->getValue();