diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index 55b1114..a0952a0 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -636,6 +636,7 @@
 void SplitEditor::selectIntv(unsigned Idx) {
   assert(Idx != 0 && "Cannot select the complement interval");
   assert(Idx < Edit->size() && "Can only select previously opened interval");
+  DEBUG(dbgs() << "    selectIntv " << OpenIdx << " -> " << Idx << '\n');
   OpenIdx = Idx;
 }
 
@@ -656,6 +657,24 @@
   return VNI->def;
 }
 
+SlotIndex SplitEditor::enterIntvAfter(SlotIndex Idx) {
+  assert(OpenIdx && "openIntv not called before enterIntvAfter");
+  DEBUG(dbgs() << "    enterIntvAfter " << Idx);
+  Idx = Idx.getBoundaryIndex();
+  VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Idx);
+  if (!ParentVNI) {
+    DEBUG(dbgs() << ": not live\n");
+    return Idx;
+  }
+  DEBUG(dbgs() << ": valno " << ParentVNI->id << '\n');
+  MachineInstr *MI = LIS.getInstructionFromIndex(Idx);
+  assert(MI && "enterIntvAfter called with invalid index");
+
+  VNInfo *VNI = defFromParent(OpenIdx, ParentVNI, Idx, *MI->getParent(),
+                              llvm::next(MachineBasicBlock::iterator(MI)));
+  return VNI->def;
+}
+
 SlotIndex SplitEditor::enterIntvAtEnd(MachineBasicBlock &MBB) {
   assert(OpenIdx && "openIntv not called before enterIntvAtEnd");
   SlotIndex End = LIS.getMBBEndIdx(&MBB);
@@ -1007,12 +1026,6 @@
         markComplexMapped(i, ParentVNI);
   }
 
-#ifndef NDEBUG
-  // Every new interval must have a def by now, otherwise the split is bogus.
-  for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I)
-    assert((*I)->hasAtLeastOneValue() && "Split interval has no value");
-#endif
-
   // Transfer the simply mapped values, check if any are skipped.
   bool Skipped = transferValues();
   if (Skipped)