Index: cfe/trunk/include/clang/Driver/Options.td
===================================================================
--- cfe/trunk/include/clang/Driver/Options.td
+++ cfe/trunk/include/clang/Driver/Options.td
@@ -1764,7 +1764,7 @@
   Flags<[CC1Option]>;
 def ivfsoverlay : JoinedOrSeparate<["-"], "ivfsoverlay">, Group<clang_i_Group>, Flags<[CC1Option]>,
   HelpText<"Overlay the virtual filesystem described by file over the real file system">;
-def i : Joined<["-"], "i">, Group<i_Group>;
+def imultilib : Separate<["-"], "imultilib">, Group<gfortran_Group>;
 def keep__private__externs : Flag<["-"], "keep_private_externs">;
 def l : JoinedOrSeparate<["-"], "l">, Flags<[LinkerInput, RenderJoined]>,
         Group<Link_Group>;
Index: cfe/trunk/test/Driver/unknown-arg.c
===================================================================
--- cfe/trunk/test/Driver/unknown-arg.c
+++ cfe/trunk/test/Driver/unknown-arg.c
@@ -1,5 +1,7 @@
-// RUN: not %clang %s -cake-is-lie -%0 -%d -HHHH -munknown-to-clang-option -print-stats -funknown-to-clang-option -### 2>&1 | \
+// RUN: not %clang %s -cake-is-lie -%0 -%d -HHHH -munknown-to-clang-option -print-stats -funknown-to-clang-option -ifoo -imultilib dir -### 2>&1 | \
 // RUN: FileCheck %s
+// RUN: %clang %s -imultilib dir -### 2>&1 | \
+// RUN: FileCheck %s --check-prefix=MULTILIB
 // RUN: not %clang %s -stdlibs=foo -hell -version -### 2>&1 | \
 // RUN: FileCheck %s --check-prefix=DID-YOU-MEAN
 // RUN: %clang_cl -cake-is-lie -%0 -%d -HHHH -munknown-to-clang-option -print-stats -funknown-to-clang-option -### -c -- %s 2>&1 | \
@@ -24,6 +26,8 @@
 // CHECK: error: unknown argument: '-munknown-to-clang-option'
 // CHECK: error: unknown argument: '-print-stats'
 // CHECK: error: unknown argument: '-funknown-to-clang-option'
+// CHECK: error: unknown argument: '-ifoo'
+// MULTILIB: warning: argument unused during compilation: '-imultilib dir'
 // DID-YOU-MEAN: error: unknown argument '-stdlibs=foo', did you mean '-stdlib=foo'?
 // DID-YOU-MEAN: error: unknown argument '-hell', did you mean '-help'?
 // DID-YOU-MEAN: error: unknown argument '-version', did you mean '--version'?