Index: llvm/trunk/include/llvm/Transforms/Utils/MemorySSA.h
===================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/MemorySSA.h
+++ llvm/trunk/include/llvm/Transforms/Utils/MemorySSA.h
@@ -246,6 +246,16 @@
     return MA->getValueID() == MemoryUseVal || MA->getValueID() == MemoryDefVal;
   }
 
+  // Sadly, these have to be public because they are needed in some of the iterators.
+  virtual bool isOptimized() const = 0;
+  virtual MemoryAccess *getOptimized() const = 0;
+  virtual void setOptimized(MemoryAccess *) = 0;
+
+  /// \brief Reset the ID of what this MemoryUse was optimized to, causing it to
+  /// be rewalked by the walker if necessary.
+  /// This really should only be called by tests.
+  virtual void resetOptimized() = 0;
+
 protected:
   friend class MemorySSA;
   friend class MemorySSAUpdater;
@@ -254,8 +264,12 @@
       : MemoryAccess(C, Vty, BB, 1), MemoryInst(MI) {
     setDefiningAccess(DMA);
   }
-
-  void setDefiningAccess(MemoryAccess *DMA) { setOperand(0, DMA); }
+  void setDefiningAccess(MemoryAccess *DMA, bool Optimized = false) {
+    setOperand(0, DMA);
+    if (!Optimized)
+      return;
+    setOptimized(DMA);
+  }
 
 private:
   Instruction *MemoryInst;
@@ -288,20 +302,18 @@
 
   void print(raw_ostream &OS) const override;
 
-  void setDefiningAccess(MemoryAccess *DMA, bool Optimized = false) {
-    if (Optimized)
-      OptimizedID = DMA->getID();
-    MemoryUseOrDef::setDefiningAccess(DMA);
+  virtual void setOptimized(MemoryAccess *DMA) override {
+    OptimizedID = DMA->getID();
   }
 
-  bool isOptimized() const {
+  virtual bool isOptimized() const override {
     return getDefiningAccess() && OptimizedID == getDefiningAccess()->getID();
   }
 
-  /// \brief Reset the ID of what this MemoryUse was optimized to, causing it to
-  /// be rewalked by the walker if necessary.
-  /// This really should only be called by tests.
-  void resetOptimized() { OptimizedID = INVALID_MEMORYACCESS_ID; }
+  virtual MemoryAccess *getOptimized() const override {
+    return getDefiningAccess();
+  }
+  virtual void resetOptimized() override { OptimizedID = INVALID_MEMORYACCESS_ID; }
 
 protected:
   friend class MemorySSA;
@@ -333,7 +345,8 @@
 
   MemoryDef(LLVMContext &C, MemoryAccess *DMA, Instruction *MI, BasicBlock *BB,
             unsigned Ver)
-      : MemoryUseOrDef(C, DMA, MemoryDefVal, MI, BB), ID(Ver) {}
+      : MemoryUseOrDef(C, DMA, MemoryDefVal, MI, BB), ID(Ver),
+        Optimized(nullptr), OptimizedID(INVALID_MEMORYACCESS_ID) {}
 
   // allocate space for exactly one operand
   void *operator new(size_t s) { return User::operator new(s, 1); }
@@ -343,6 +356,17 @@
     return MA->getValueID() == MemoryDefVal;
   }
 
+  virtual void setOptimized(MemoryAccess *MA) override {
+    Optimized = MA;
+    OptimizedID = getDefiningAccess()->getID();
+  }
+  virtual MemoryAccess *getOptimized() const override { return Optimized; }
+  virtual bool isOptimized() const override {
+    return getOptimized() && OptimizedID == getDefiningAccess()->getID();
+  }
+  virtual void resetOptimized() override { OptimizedID = INVALID_MEMORYACCESS_ID; }
+
+
   void print(raw_ostream &OS) const override;
 
 protected:
@@ -352,6 +376,8 @@
 
 private:
   const unsigned ID;
+  MemoryAccess *Optimized;
+  unsigned int OptimizedID;
 };
 
 template <>
@@ -1075,10 +1101,15 @@
 
   def_chain_iterator &operator++() {
     // N.B. liveOnEntry has a null defining access.
-    if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
-      MA = MUD->getDefiningAccess();
-    else
+    if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA)) {
+      if (MUD->isOptimized())
+        MA = MUD->getOptimized();
+      else
+        MA = MUD->getDefiningAccess();
+    } else {
       MA = nullptr;
+    }
+
     return *this;
   }
 
Index: llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp
+++ llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp
@@ -2181,9 +2181,9 @@
   // If this is an already optimized use or def, return the optimized result.
   // Note: Currently, we do not store the optimized def result because we'd need
   // a separate field, since we can't use it as the defining access.
-  if (MemoryUse *MU = dyn_cast<MemoryUse>(StartingAccess))
-    if (MU->isOptimized())
-      return MU->getDefiningAccess();
+  if (auto *MUD = dyn_cast<MemoryUseOrDef>(StartingAccess))
+    if (MUD->isOptimized())
+      return MUD->getOptimized();
 
   const Instruction *I = StartingAccess->getMemoryInst();
   UpwardsMemoryQuery Q(I, StartingAccess);
@@ -2199,8 +2199,8 @@
   if (isUseTriviallyOptimizableToLiveOnEntry(*MSSA->AA, I)) {
     MemoryAccess *LiveOnEntry = MSSA->getLiveOnEntryDef();
     Cache.insert(StartingAccess, LiveOnEntry, Q.StartingLoc, Q.IsCall);
-    if (MemoryUse *MU = dyn_cast<MemoryUse>(StartingAccess))
-      MU->setDefiningAccess(LiveOnEntry, true);
+    if (auto *MUD = dyn_cast<MemoryUseOrDef>(StartingAccess))
+      MUD->setDefiningAccess(LiveOnEntry, true);
     return LiveOnEntry;
   }
 
@@ -2217,8 +2217,8 @@
   DEBUG(dbgs() << *DefiningAccess << "\n");
   DEBUG(dbgs() << "Final Memory SSA clobber for " << *I << " is ");
   DEBUG(dbgs() << *Result << "\n");
-  if (MemoryUse *MU = dyn_cast<MemoryUse>(StartingAccess))
-    MU->setDefiningAccess(Result, true);
+  if (auto *MUD = dyn_cast<MemoryUseOrDef>(StartingAccess))
+    MUD->setDefiningAccess(Result, true);
 
   return Result;
 }
Index: llvm/trunk/lib/Transforms/Utils/MemorySSAUpdater.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/MemorySSAUpdater.cpp
+++ llvm/trunk/lib/Transforms/Utils/MemorySSAUpdater.cpp
@@ -451,8 +451,8 @@
 
     while (!MA->use_empty()) {
       Use &U = *MA->use_begin();
-      if (MemoryUse *MU = dyn_cast<MemoryUse>(U.getUser()))
-        MU->resetOptimized();
+      if (auto *MUD = dyn_cast<MemoryUseOrDef>(U.getUser()))
+        MUD->resetOptimized();
       U.set(NewDefTarget);
     }
   }