Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -1226,7 +1226,7 @@
   Opts.CPlusPlus1z = Std.isCPlusPlus1z();
   Opts.Digraphs = Std.hasDigraphs();
   Opts.GNUMode = Std.isGNUMode();
-  Opts.GNUInline = !Std.isC99();
+  Opts.GNUInline = Std.isC89();
   Opts.HexFloats = Std.hasHexFloats();
   Opts.ImplicitInt = Std.hasImplicitInt();
 
@@ -1409,8 +1409,13 @@
         (Opts.ObjCRuntime.getKind() == ObjCRuntime::FragileMacOSX);
   }
     
-  if (Args.hasArg(OPT_fgnu89_inline))
-    Opts.GNUInline = 1;
+  if (Args.hasArg(OPT_fgnu89_inline)) {
+    if (Opts.CPlusPlus)
+      Diags.Report(diag::err_drv_argument_not_allowed_with) << "-fgnu89-inline"
+                                                            << "C++/ObjC++";
+    else
+      Opts.GNUInline = 1;
+  }
 
   if (Args.hasArg(OPT_fapple_kext)) {
     if (!Opts.CPlusPlus)
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -2713,7 +2713,7 @@
   // UndefinedButUsed.
   if (!Old->isInlined() && New->isInlined() &&
       !New->hasAttr<GNUInlineAttr>() &&
-      (getLangOpts().CPlusPlus || !getLangOpts().GNUInline) &&
+      !getLangOpts().GNUInline &&
       Old->isUsed(false) &&
       !Old->isDefined() && !New->isThisDeclarationADefinition())
     UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
@@ -10586,7 +10586,7 @@
       if (!FD->isExternallyVisible())
         UndefinedButUsed.erase(FD);
       else if (FD->isInlined() &&
-               (LangOpts.CPlusPlus || !LangOpts.GNUInline) &&
+               !LangOpts.GNUInline &&
                (!FD->getPreviousDecl()->hasAttr<GNUInlineAttr>()))
         UndefinedButUsed.erase(FD);
     }
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -12232,7 +12232,7 @@
     if (mightHaveNonExternalLinkage(Func))
       UndefinedButUsed.insert(std::make_pair(Func->getCanonicalDecl(), Loc));
     else if (Func->getMostRecentDecl()->isInlined() &&
-             (LangOpts.CPlusPlus || !LangOpts.GNUInline) &&
+             !LangOpts.GNUInline &&
              !Func->getMostRecentDecl()->hasAttr<GNUInlineAttr>())
       UndefinedButUsed.insert(std::make_pair(Func->getCanonicalDecl(), Loc));
   }
Index: test/CodeGen/inline.c
===================================================================
--- test/CodeGen/inline.c
+++ test/CodeGen/inline.c
@@ -49,6 +49,7 @@
 // CHECK3-NOT: unreferenced
 // CHECK3-LABEL: define void @_Z10gnu_inlinev()
 // CHECK3-LABEL: define available_externally void @_Z13gnu_ei_inlinev()
+// CHECK3-NOT: @_Z5testCv
 // CHECK3-LABEL: define linkonce_odr i32 @_Z2eiv()
 
 // RUN: echo "MS C Mode tests:"
Index: test/Frontend/gnu-inline.c
===================================================================
--- /dev/null
+++ test/Frontend/gnu-inline.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -std=c89 -fsyntax-only -x c -E -dM %s | FileCheck --check-prefix=GNU-INLINE %s
+// RUN: %clang_cc1 -std=c99 -fsyntax-only -x c -E -dM %s | FileCheck --check-prefix=STDC-INLINE %s
+// RUN: %clang_cc1 -std=c99 -fgnu89-inline -fsyntax-only -x c -E -dM %s | FileCheck --check-prefix=GNU-INLINE %s
+// RUN: %clang_cc1 -fsyntax-only -x c++ -E -dM %s | FileCheck --check-prefix=STDC-INLINE %s
+// RUN: not %clang_cc1 -fgnu89-inline -fsyntax-only -x c++ %s 2>&1 | FileCheck --check-prefix=CXX %s
+
+// CXX: '-fgnu89-inline' not allowed with 'C++/ObjC++'
+
+// STDC-INLINE-NOT: __GNUC_GNU_INLINE__
+// STDC-INLINE: #define __GNUC_STDC_INLINE__ 1
+// STDC-INLINE-NOT: __GNUC_GNU_INLINE__
+
+// GNU-INLINE-NOT: __GNUC_STDC_INLINE__
+// GNU-INLINE: #define __GNUC_GNU_INLINE__ 1
+// GNU-INLINE-NOT: __GNUC_STDC_INLINE__