diff --git a/lib/CodeGen/CGVTT.cpp b/lib/CodeGen/CGVTT.cpp
index 9714bd9..96c104b 100644
--- a/lib/CodeGen/CGVTT.cpp
+++ b/lib/CodeGen/CGVTT.cpp
@@ -46,7 +46,8 @@
   llvm::DenseMap<std::pair<const CXXRecordDecl *, BaseSubobject>, uint64_t> 
     CtorVtableAddressPoints;
   
-  llvm::Constant *getCtorVtable(const BaseSubobject &Base) {
+  llvm::Constant *getCtorVtable(const BaseSubobject &Base,
+                                bool BaseIsVirtual) {
     if (!GenerateDefinition)
       return 0;
 
@@ -54,7 +55,7 @@
     if (!CtorVtable) {
       // Build the vtable.
       CGVtableInfo::CtorVtableInfo Info
-        = CGM.getVtableInfo().getCtorVtable(Class, Base);
+        = CGM.getVtableInfo().getCtorVtable(Class, Base, BaseIsVirtual);
       
       CtorVtable = Info.Vtable;
       
@@ -166,7 +167,7 @@
         if (BaseMorallyVirtual || VtblClass == Class)
           init = BuildVtablePtr(vtbl, VtblClass, Base, BaseOffset);
         else {
-          init = getCtorVtable(BaseSubobject(Base, BaseOffset));
+          init = getCtorVtable(BaseSubobject(Base, BaseOffset), i->isVirtual());
           
           subvtbl = init;
           subVtblClass = Base;
@@ -186,7 +187,8 @@
 
   /// BuiltVTT - Add the VTT to Inits.  Offset is the offset in bits to the
   /// currnet object we're working on.
-  void BuildVTT(const CXXRecordDecl *RD, uint64_t Offset, bool MorallyVirtual) {
+  void BuildVTT(const CXXRecordDecl *RD, uint64_t Offset, bool BaseIsVirtual,
+                bool MorallyVirtual) {
     // Itanium C++ ABI 2.6.2:
     //   An array of virtual table addresses, called the VTT, is declared for 
     //   each class type that has indirect or direct virtual base classes.
@@ -204,7 +206,8 @@
       Vtable = ClassVtbl;
       VtableClass = Class;
     } else {
-      Vtable = getCtorVtable(BaseSubobject(RD, Offset));
+      Vtable = getCtorVtable(BaseSubobject(RD, Offset), 
+                             /*IsVirtual=*/BaseIsVirtual);
       VtableClass = RD;
     }
     
@@ -235,7 +238,7 @@
       const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
       uint64_t BaseOffset = Offset + Layout.getBaseClassOffset(Base);
       
-      BuildVTT(Base, BaseOffset, MorallyVirtual);
+      BuildVTT(Base, BaseOffset, /*BaseIsVirtual=*/false, MorallyVirtual);
     }
   }
 
@@ -249,7 +252,7 @@
       if (i->isVirtual() && !SeenVBase.count(Base)) {
         SeenVBase.insert(Base);
         uint64_t BaseOffset = BLayout.getVBaseClassOffset(Base);
-        BuildVTT(Base, BaseOffset, false);
+        BuildVTT(Base, BaseOffset, /*BaseIsVirtual=*/true, false);
       }
       VirtualVTTs(Base);
     }
@@ -335,13 +338,13 @@
 
 CGVtableInfo::CtorVtableInfo 
 CGVtableInfo::getCtorVtable(const CXXRecordDecl *RD, 
-                            const BaseSubobject &Base) {
+                            const BaseSubobject &Base, bool BaseIsVirtual) {
   CtorVtableInfo Info;
   
   Info.Vtable = GenerateVtable(llvm::GlobalValue::InternalLinkage,
                                /*GenerateDefinition=*/true,
                                RD, Base.getBase(), Base.getBaseOffset(),
-                               Info.AddressPoints);
+                               BaseIsVirtual, Info.AddressPoints);
   return Info;
 }
 
diff --git a/lib/CodeGen/CGVtable.cpp b/lib/CodeGen/CGVtable.cpp
index ad035cd..6fc81d4 100644
--- a/lib/CodeGen/CGVtable.cpp
+++ b/lib/CodeGen/CGVtable.cpp
@@ -1076,6 +1076,10 @@
   /// holds the offset from the layout class to the most derived class.
   const uint64_t MostDerivedClassOffset;
   
+  /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual 
+  /// base. (This only makes sense when building a construction vtable).
+  bool MostDerivedClassIsVirtual;
+  
   /// LayoutClass - The class we're using for layout information. Will be 
   /// different than the most derived class if we're building a construction
   /// vtable.
@@ -1214,7 +1218,7 @@
   void AddMethods(BaseSubobject Base, BaseSubobject FirstBaseInPrimaryBaseChain,
                   PrimaryBasesSetVectorTy &PrimaryBases);
 
-  // LayoutVtable - Layout the vtable for the most derived class, including its
+  // LayoutVtable - Layout the vtable for the given base class, including its
   // secondary vtables and any vtables for virtual bases.
   void LayoutVtable();
 
@@ -1245,11 +1249,13 @@
 
 public:
   VtableBuilder(CGVtableInfo &VtableInfo, const CXXRecordDecl *MostDerivedClass,
-                uint64_t MostDerivedClassOffset, 
+                uint64_t MostDerivedClassOffset, bool MostDerivedClassIsVirtual,
                 const CXXRecordDecl *LayoutClass)
     : VtableInfo(VtableInfo), MostDerivedClass(MostDerivedClass),
-    MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass),
-    Context(MostDerivedClass->getASTContext()), Overriders(MostDerivedClass) {
+    MostDerivedClassOffset(MostDerivedClassOffset), 
+    MostDerivedClassIsVirtual(MostDerivedClassIsVirtual), 
+    LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()), 
+    Overriders(MostDerivedClass) {
 
     LayoutVtable();
   }
@@ -1678,7 +1684,7 @@
 
 void VtableBuilder::LayoutVtable() {
   LayoutPrimaryAndAndSecondaryVtables(BaseSubobject(MostDerivedClass, 0),
-                                      /*BaseIsVirtual=*/false);
+                                      MostDerivedClassIsVirtual);
   
   VisitedVirtualBasesSetTy VBases;
   
@@ -3318,16 +3324,23 @@
                              bool GenerateDefinition,
                              const CXXRecordDecl *LayoutClass,
                              const CXXRecordDecl *RD, uint64_t Offset,
+                             bool IsVirtual,
                              AddressPointsMapTy& AddressPoints) {
   if (GenerateDefinition) {
     if (LayoutClass == RD) {
-      VtableBuilder Builder(*this, RD, Offset, LayoutClass);
+      assert(!IsVirtual && 
+             "Can't only have a virtual base in construction vtables!");
+      VtableBuilder Builder(*this, RD, Offset, 
+                            /*MostDerivedClassIsVirtual=*/false,
+                            LayoutClass);
 
       if (CGM.getLangOptions().DumpVtableLayouts)
         Builder.dumpLayout(llvm::errs());
     } else if (CGM.getLangOptions().DumpVtableLayouts) {
       // We only build construction vtables when dumping vtable layouts for now.
-      VtableBuilder Builder(*this, RD, Offset, LayoutClass);
+      VtableBuilder Builder(*this, RD, Offset, 
+                            /*MostDerivedClassIsVirtual=*/IsVirtual,
+                            LayoutClass);
       Builder.dumpLayout(llvm::errs());
     }
   }
@@ -3390,6 +3403,7 @@
   
   AddressPointsMapTy AddressPoints;
   Vtable = GenerateVtable(Linkage, /*GenerateDefinition=*/true, RD, RD, 0,
+                          /*IsVirtual=*/false,
                           AddressPoints);
   GenerateVTT(Linkage, /*GenerateDefinition=*/true, RD);  
 }
@@ -3401,7 +3415,7 @@
     AddressPointsMapTy AddressPoints;
     Vtable = GenerateVtable(llvm::GlobalValue::ExternalLinkage, 
                             /*GenerateDefinition=*/false, RD, RD, 0,
-                            AddressPoints);
+                            /*IsVirtual=*/false, AddressPoints);
   }
 
   return Vtable;
diff --git a/lib/CodeGen/CGVtable.h b/lib/CodeGen/CGVtable.h
index 471d638..6ccb011 100644
--- a/lib/CodeGen/CGVtable.h
+++ b/lib/CodeGen/CGVtable.h
@@ -185,7 +185,7 @@
   llvm::GlobalVariable *
   GenerateVtable(llvm::GlobalVariable::LinkageTypes Linkage,
                  bool GenerateDefinition, const CXXRecordDecl *LayoutClass, 
-                 const CXXRecordDecl *RD, uint64_t Offset,
+                 const CXXRecordDecl *RD, uint64_t Offset, bool IsVirtual,
                  AddressPointsMapTy& AddressPoints);
 
   llvm::GlobalVariable *GenerateVTT(llvm::GlobalVariable::LinkageTypes Linkage,
@@ -239,7 +239,8 @@
   };
   
   CtorVtableInfo getCtorVtable(const CXXRecordDecl *RD, 
-                               const BaseSubobject &Base);
+                               const BaseSubobject &Base,
+                               bool BaseIsVirtual);
   
   llvm::GlobalVariable *getVTT(const CXXRecordDecl *RD);