diff --git a/include/llvm/CodeGen/SlotIndexes.h b/include/llvm/CodeGen/SlotIndexes.h
index b46d1538673..690bee66c0f 100644
--- a/include/llvm/CodeGen/SlotIndexes.h
+++ b/include/llvm/CodeGen/SlotIndexes.h
@@ -602,21 +602,21 @@ namespace llvm {
     void insertMBBInMaps(MachineBasicBlock *mbb) {
       MachineFunction::iterator nextMBB =
         llvm::next(MachineFunction::iterator(mbb));
+
+      IndexListEntry *nextEntry = 0;
+      if (nextMBB == mbb->getParent()->end())
+        nextEntry = &indexList.back();
+      else
+        nextEntry = getMBBStartIdx(nextMBB).listEntry();
+
       IndexListEntry *startEntry = createEntry(0, 0);
       IndexListEntry *stopEntry = createEntry(0, 0);
-      IndexListEntry *nextEntry = 0;
 
-      if (nextMBB == mbb->getParent()->end()) {
-        nextEntry = indexList.end();
-      } else {
-        nextEntry = getMBBStartIdx(nextMBB).listEntry();
-      }
-
-      indexList.insert(nextEntry, startEntry);
-      indexList.insert(nextEntry, stopEntry);
+      indexList.insertAfter(nextEntry, startEntry);
+      indexList.insertAfter(startEntry, stopEntry);
 
       SlotIndex startIdx(startEntry, SlotIndex::Slot_Block);
-      SlotIndex endIdx(nextEntry, SlotIndex::Slot_Block);
+      SlotIndex endIdx(stopEntry, SlotIndex::Slot_Block);
 
       assert(unsigned(mbb->getNumber()) == MBBRanges.size() &&
              "Blocks must be added in order");
@@ -624,6 +624,8 @@ namespace llvm {
 
       idx2MBBMap.push_back(IdxMBBPair(startIdx, mbb));
 
+      // FIXME: Renumber locally instead of renumbering the whole function every
+      // time a new block is inserted.
       renumberIndexes();
       std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
     }
diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index 7e9fb20ffe8..2534a740058 100644
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -662,6 +662,9 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
         " BB#" << getNumber()
         << " -- BB#" << NMBB->getNumber()
         << " -- BB#" << Succ->getNumber() << '\n');
+  SlotIndexes *Indexes = P->getAnalysisIfAvailable<SlotIndexes>();
+  if (Indexes)
+    Indexes->insertMBBInMaps(NMBB);
 
   // On some targets like Mips, branches may kill virtual registers. Make sure
   // that LiveVariables is properly updated after updateTerminator replaces the
@@ -697,6 +700,17 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
   if (!NMBB->isLayoutSuccessor(Succ)) {
     Cond.clear();
     MF->getTarget().getInstrInfo()->InsertBranch(*NMBB, Succ, NULL, Cond, dl);
+
+    if (Indexes) {
+      for (instr_iterator I = NMBB->instr_begin(), E = NMBB->instr_end();
+           I != E; ++I) {
+        // Some instructions may have been moved to NMBB by updateTerminator(),
+        // so we first remove any instruction that already has an index.
+        if (Indexes->hasIndex(I))
+          Indexes->removeMachineInstrFromMaps(I);
+        Indexes->insertMachineInstrInMaps(I);
+      }
+    }
   }
 
   // Fix PHI nodes in Succ so they refer to NMBB instead of this