diff --git a/lib/CodeGen/Mangle.cpp b/lib/CodeGen/Mangle.cpp
index 88e4c64..cf7a74b 100644
--- a/lib/CodeGen/Mangle.cpp
+++ b/lib/CodeGen/Mangle.cpp
@@ -108,7 +108,8 @@
   void mangleFunctionEncoding(const FunctionDecl *FD);
   void mangleName(const NamedDecl *ND);
   void mangleType(QualType T);
-
+  void mangleNameOrStandardSubstitution(const NamedDecl *ND);
+  
 private:
   bool mangleSubstitution(const NamedDecl *ND);
   bool mangleSubstitution(QualType T);
@@ -1025,6 +1026,11 @@
     addSubstitution(T);
 }
 
+void CXXNameMangler::mangleNameOrStandardSubstitution(const NamedDecl *ND) {
+  if (!mangleStandardSubstitution(ND))
+    mangleName(ND);
+}
+
 void CXXNameMangler::mangleType(const BuiltinType *T) {
   //  <type>         ::= <builtin-type>
   //  <builtin-type> ::= v  # void
@@ -2137,7 +2143,7 @@
   // <special-name> ::= TV <type>  # virtual table
   CXXNameMangler Mangler(*this, Res);
   Mangler.getStream() << "_ZTV";
-  Mangler.mangleName(RD);
+  Mangler.mangleNameOrStandardSubstitution(RD);
 }
 
 void MangleContext::mangleCXXVTT(const CXXRecordDecl *RD,
@@ -2145,7 +2151,7 @@
   // <special-name> ::= TT <type>  # VTT structure
   CXXNameMangler Mangler(*this, Res);
   Mangler.getStream() << "_ZTT";
-  Mangler.mangleName(RD);
+  Mangler.mangleNameOrStandardSubstitution(RD);
 }
 
 void MangleContext::mangleCXXCtorVTable(const CXXRecordDecl *RD, int64_t Offset,
@@ -2154,10 +2160,10 @@
   // <special-name> ::= TC <type> <offset number> _ <base type>
   CXXNameMangler Mangler(*this, Res);
   Mangler.getStream() << "_ZTC";
-  Mangler.mangleName(RD);
+  Mangler.mangleNameOrStandardSubstitution(RD);
   Mangler.getStream() << Offset;
   Mangler.getStream() << '_';
-  Mangler.mangleName(Type);
+  Mangler.mangleNameOrStandardSubstitution(Type);
 }
 
 void MangleContext::mangleCXXRTTI(QualType Ty,
diff --git a/test/CodeGenCXX/mangle-subst-std.cpp b/test/CodeGenCXX/mangle-subst-std.cpp
index 062610b..4c15eaa 100644
--- a/test/CodeGenCXX/mangle-subst-std.cpp
+++ b/test/CodeGenCXX/mangle-subst-std.cpp
@@ -1,5 +1,16 @@
 // RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-apple-darwin9 | FileCheck %s
 
+// Check mangling of Vtables, VTTs, and construction vtables that
+// involve standard substitutions.
+
+// CHECK: @_ZTVSd = weak_odr constant 
+// CHECK: @_ZTCSd0_Si = internal constant 
+// CHECK: @_ZTCSd16_So = internal constant
+// CHECK: @_ZTTSd = weak_odr constant
+// CHECK: @_ZTVSo = weak_odr constant
+// CHECK: @_ZTTSo = weak_odr constant
+// CHECK: @_ZTVSi = weak_odr constant
+// CHECK: @_ZTTSi = weak_odr constant
 namespace std {
   struct A { A(); };
   
@@ -32,9 +43,30 @@
 void f(std::string) { }
 
 namespace std {
-  template<typename, typename> struct basic_istream { };
-  template<typename, typename> struct basic_ostream { };
-  template<typename, typename> struct basic_iostream { };
+  template<typename, typename> struct basic_ios { 
+    basic_ios(int);
+    virtual ~basic_ios();
+  };
+  template<typename charT, typename traits = char_traits<charT> > 
+  struct basic_istream : virtual public basic_ios<charT, traits> { 
+    basic_istream(int x) : basic_ios<charT, traits>(x), stored(x) { }
+
+    int stored;
+  };
+  template<typename charT, typename traits = char_traits<charT> > 
+  struct basic_ostream : virtual public basic_ios<charT, traits> { 
+    basic_ostream(int x) : basic_ios<charT, traits>(x), stored(x) { }
+
+    float stored;
+  };
+
+  template<typename charT, typename traits = char_traits<charT> > 
+    struct basic_iostream : public basic_istream<charT, traits>, 
+                            public basic_ostream<charT, traits> { 
+    basic_iostream(int x) : basic_istream<charT, traits>(x),
+                            basic_ostream<charT, traits>(x),
+                            basic_ios<charT, traits>(x) { }
+  };
 }
 
 // CHECK: _Z1fSi
@@ -61,3 +93,9 @@
 template<typename, typename, typename> struct basic_string { };
 typedef basic_string<char, std::char_traits<char>, std::allocator<char> > not_string;
 void f(not_string) { }
+
+// Manglings for instantiations caused by this function are at the
+// top of the test.
+void create_streams() {
+  std::basic_iostream<char> bio(17);
+}