Index: lib/CodeGen/CalcSpillWeights.cpp
===================================================================
--- lib/CodeGen/CalcSpillWeights.cpp
+++ lib/CodeGen/CalcSpillWeights.cpp
@@ -74,12 +74,12 @@
 }
 
 // Check if all values in LI are rematerializable
-static bool isRematerializable(const LiveInterval &LI,
-                               const LiveIntervals &LIS,
-                               VirtRegMap *VRM,
+static bool isRematerializable(const LiveInterval &LI, const LiveIntervals &LIS,
+                               const VirtRegMap *VRM,
                                const TargetInstrInfo &TII) {
   unsigned Reg = LI.reg;
   unsigned Original = VRM ? VRM->getOriginal(Reg) : 0;
+  SmallPtrSet<const VNInfo *, 4> Visited;
   for (LiveInterval::const_vni_iterator I = LI.vni_begin(), E = LI.vni_end();
        I != E; ++I) {
     const VNInfo *VNI = *I;
@@ -113,6 +113,8 @@
         const LiveInterval &SrcLI = LIS.getInterval(Reg);
         LiveQueryResult SrcQ = SrcLI.Query(VNI->def);
         VNI = SrcQ.valueIn();
+        if (!Visited.insert(VNI).second)
+          break;
         assert(VNI && "Copy from non-existing value");
         if (VNI->isPHIDef())
           return false;