diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp
index 91805a93edf..8441e49bbc6 100644
--- a/lib/CodeGen/PHIElimination.cpp
+++ b/lib/CodeGen/PHIElimination.cpp
@@ -145,6 +145,10 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB,
       LV->addVirtualRegisterDead(DestReg, PHICopy);
       LV->removeVirtualRegistersDead(MPhi);
     }
+    
+    // Realize that the destination register is defined by the PHI copy now, not
+    // the PHI itself.
+    LV->getVarInfo(DestReg).DefInst = PHICopy;
   }
 
   // Adjust the VRegPHIUseCount map to account for the removal of this PHI
diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index 26498b7ec1f..f27ae2a8212 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -393,6 +393,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
       
       // Otherwise, reload it and remember that we have it.
       PhysReg = VRM.getPhys(VirtReg);
+      assert(PhysReg && "Must map virtreg to physreg!");
       const TargetRegisterClass* RC =
         MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);