diff --git a/lib/CodeGen/LiveInterval.cpp b/lib/CodeGen/LiveInterval.cpp
index c9e98bc..53ffbe3 100644
--- a/lib/CodeGen/LiveInterval.cpp
+++ b/lib/CodeGen/LiveInterval.cpp
@@ -288,26 +288,24 @@
 void LiveInterval::join(LiveInterval &Other, int *LHSValNoAssignments,
                         int *RHSValNoAssignments, 
                         SmallVector<VNInfo*, 16> &NewVNInfo) {
-
-  // There might be some dead val#, create VNInfo for them.
-  for (unsigned i = 0, e = NewVNInfo.size(); i != e; ++i) {
-    VNInfo *VNI = NewVNInfo[i];
-    if (!VNI) {
-      VNI = new VNInfo(this, i, ~1U, 0);
-      NewVNInfo[i] = VNI;
-    }
-  }
-
   // Determine if any of our live range values are mapped.  This is uncommon, so
-  // we want to avoid the interval scan if not.
+  // we want to avoid the interval scan if not. 
   bool MustMapCurValNos = false;
-  for (vni_iterator i = vni_begin(), e = vni_end(); i != e; ++i) {
-    VNInfo *VNI = *i;
-    unsigned VN = VNI->id;
-    if (VNI->def == ~1U) continue;  // tombstone value #
-    if (VNI != NewVNInfo[LHSValNoAssignments[VN]]) {
+  unsigned NumVals = getNumValNums();
+  unsigned NumNewVals = NewVNInfo.size();
+  for (unsigned i = 0; i != NumVals; ++i) {
+    unsigned LHSValID = LHSValNoAssignments[i];
+    if (i != LHSValID ||
+        (NewVNInfo[LHSValID] && NewVNInfo[LHSValID]->parent != this))
       MustMapCurValNos = true;
-      break;
+
+    // There might be some dead val#, create VNInfo for them.
+    if (i < NumNewVals) {
+      VNInfo *VNI = NewVNInfo[i];
+      if (!VNI) {
+        VNI = new VNInfo(this, i, ~1U, 0);
+        NewVNInfo[i] = VNI;
+      }
     }
   }
 
@@ -342,19 +340,34 @@
   }
 
   // Remember assignements because val# ids are changing.
-  std::vector<unsigned> OtherAssignments;
+  SmallVector<unsigned, 16> OtherAssignments;
   for (iterator I = Other.begin(), E = Other.end(); I != E; ++I)
     OtherAssignments.push_back(RHSValNoAssignments[I->valno->id]);
 
   // Update val# info. Renumber them and make sure they all belong to this
   // LiveInterval now.
-  valnos.clear();
-  for (unsigned i = 0, e = NewVNInfo.size(); i != e; ++i) {
+  for (unsigned i = 0; i != NumVals; ++i) {
+    if (i == NumNewVals)
+      break;
     VNInfo *VNI = NewVNInfo[i];
-    VNI->parent = this;
-    VNI->id = i;  // Renumber val#.
+    if (VNI->parent != this || VNI->id != i) {
+      VNI->parent = this;
+      VNI->id = i;  // Renumber val#.
+      valnos[i] = VNI;
+    }
+  }
+  for (unsigned i = NumVals; i < NumNewVals; ++i) {
+    VNInfo *VNI = NewVNInfo[i];
+    if (!VNI)
+      VNI = new VNInfo(this, i, ~1U, 0);
+    else {
+      VNI->parent = this;
+      VNI->id = i;  // Renumber val#.
+    }
     valnos.push_back(VNI);
   }
+  if (NumNewVals < NumVals)
+    valnos.resize(NumNewVals);  // shrinkify
 
   // Okay, now insert the RHS live ranges into the LHS.
   iterator InsertPos = begin();
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 052573a..03e416b 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -682,8 +682,9 @@
     assert(RHSValID != -1 && "Didn't find value #?");
     RHSValNoAssignments[0] = RHSValID;
     if (RHSVal0DefinedFromLHS != -1) {
-      RHSValsDefinedFromLHS[RHSValNoInfo0] =
-        LHS.getLiveRangeContaining(RHSValNoInfo0->def-1)->valno;
+      // This path doesn't go through ComputeUltimateVN so just set
+      // it to anything.
+      RHSValsDefinedFromLHS[RHSValNoInfo0] = (VNInfo*)1;
     }
   } else {
     // Loop over the value numbers of the LHS, seeing if any are defined from
@@ -798,31 +799,32 @@
     }
   }
 
-  // Update kill info. Some live ranges are extended due to copy coalescing.
-  for (DenseMap<VNInfo*, VNInfo*>::iterator I = RHSValsDefinedFromLHS.begin(),
-         E = RHSValsDefinedFromLHS.end(); I != E; ++I) {
-    VNInfo *VNI = I->first;
-    unsigned RHSValID = RHSValNoAssignments[VNI->id];
-    LiveInterval::removeKill(*NewVNInfo[RHSValID], VNI->def);
-    LHS.addKills(*NewVNInfo[RHSValID], VNI->kills);
-  }
-
-  for (DenseMap<VNInfo*, VNInfo*>::iterator I = LHSValsDefinedFromRHS.begin(),
-         E = LHSValsDefinedFromRHS.end(); I != E; ++I) {
-    VNInfo *VNI = I->first;
-    unsigned LHSValID = LHSValNoAssignments[VNI->id];
-    LiveInterval::removeKill(*NewVNInfo[LHSValID], VNI->def);
-    RHS.addKills(*NewVNInfo[LHSValID], VNI->kills);
-  }
-
   // If we get here, we know that we can coalesce the live ranges.  Ask the
   // intervals to coalesce themselves now.
   if ((RHS.ranges.size() > LHS.ranges.size() &&
       MRegisterInfo::isVirtualRegister(LHS.reg)) ||
       MRegisterInfo::isPhysicalRegister(RHS.reg)) {
+    // Update kill info. Some live ranges are extended due to copy coalescing.
+    for (DenseMap<VNInfo*, VNInfo*>::iterator I = LHSValsDefinedFromRHS.begin(),
+           E = LHSValsDefinedFromRHS.end(); I != E; ++I) {
+      VNInfo *VNI = I->first;
+      unsigned LHSValID = LHSValNoAssignments[VNI->id];
+      LiveInterval::removeKill(*NewVNInfo[LHSValID], VNI->def);
+      RHS.addKills(*NewVNInfo[LHSValID], VNI->kills);
+    }
+
     RHS.join(LHS, &RHSValNoAssignments[0], &LHSValNoAssignments[0], NewVNInfo);
     Swapped = true;
   } else {
+    // Update kill info. Some live ranges are extended due to copy coalescing.
+    for (DenseMap<VNInfo*, VNInfo*>::iterator I = RHSValsDefinedFromLHS.begin(),
+           E = RHSValsDefinedFromLHS.end(); I != E; ++I) {
+      VNInfo *VNI = I->first;
+      unsigned RHSValID = RHSValNoAssignments[VNI->id];
+      LiveInterval::removeKill(*NewVNInfo[RHSValID], VNI->def);
+      LHS.addKills(*NewVNInfo[RHSValID], VNI->kills);
+    }
+
     LHS.join(RHS, &LHSValNoAssignments[0], &RHSValNoAssignments[0], NewVNInfo);
     Swapped = false;
   }