diff --git a/clang/lib/CodeGen/CGVtable.cpp b/clang/lib/CodeGen/CGVtable.cpp
index 2e4cb61b1f6f..47509616c502 100644
--- a/clang/lib/CodeGen/CGVtable.cpp
+++ b/clang/lib/CodeGen/CGVtable.cpp
@@ -3881,13 +3881,6 @@ void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk)
 
 void CodeGenVTables::EmitThunks(GlobalDecl GD)
 {
-  // FIXME: We use the -fdump-vtable-layouts flag to trigger the new thunk
-  // building code for now.
-  if (!CGM.getLangOptions().DumpVtableLayouts) {
-    CGM.BuildThunksForVirtual(GD);
-    return;
-  }
-
   const CXXMethodDecl *MD = 
     cast<CXXMethodDecl>(GD.getDecl())->getCanonicalDecl();
 
diff --git a/clang/test/CodeGenCXX/thunks.cpp b/clang/test/CodeGenCXX/thunks.cpp
new file mode 100644
index 000000000000..2389839921b6
--- /dev/null
+++ b/clang/test/CodeGenCXX/thunks.cpp
@@ -0,0 +1,116 @@
+// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck %s
+
+namespace Test1 {
+
+// Check that we emit a non-virtual thunk for C::f.
+
+struct A {
+  virtual void f();
+};
+
+struct B {
+  virtual void f();
+};
+
+struct C : A, B {
+  virtual void c();
+  
+  virtual void f();
+};
+
+// CHECK: define weak void @_ZThn8_N5Test11C1fEv(
+void C::f() { }
+
+}
+
+namespace Test2 {
+
+// Check that we emit a thunk for B::f since it's overriding a virtual base.
+
+struct A {
+  virtual void f();
+};
+
+struct B : virtual A {
+  virtual void b();
+  virtual void f();
+};
+
+// CHECK: define weak void @_ZTv0_n24_N5Test21B1fEv(
+void B::f() { }
+
+}
+
+namespace Test3 {
+
+// Check that we emit a covariant thunk for B::f.
+
+struct V1 { };
+struct V2 : virtual V1 { };
+
+struct A {
+  virtual V1 *f();
+};
+
+struct B : A {
+  virtual void b();
+  
+  virtual V2 *f();
+};
+
+// CHECK: define weak %{{.*}}* @_ZTch0_v0_n24_N5Test31B1fEv(
+V2 *B::f() { return 0; }
+
+}
+
+namespace Test4 {
+
+// Check that the thunk for 'C::f' has the same visibility as the function itself.
+
+struct A {
+  virtual void f();
+};
+
+struct B {
+  virtual void f();
+};
+
+struct __attribute__((visibility("protected"))) C : A, B {
+  virtual void c();
+  
+  virtual void f();
+};
+
+// CHECK: define weak protected void @_ZThn8_N5Test41C1fEv(
+void C::f() { }
+
+}
+
+// Check that the thunk gets internal linkage.
+namespace {
+
+struct A {
+  virtual void f();
+};
+
+struct B {
+  virtual void f();
+};
+
+struct C : A, B {
+  virtual void c();
+
+  virtual void f();
+};
+
+// CHECK: define internal void @_ZThn8_N12_GLOBAL__N_11C1fEv(
+void C::f() { }
+
+}
+
+// Force C::f to be used.
+void f() { 
+  C c; 
+  
+  c.f();
+}