Index: include/llvm/Analysis/LoopInfo.h
===================================================================
--- include/llvm/Analysis/LoopInfo.h
+++ include/llvm/Analysis/LoopInfo.h
@@ -754,6 +754,28 @@
 
     return true;
   }
+  
+  /// Checks if using a specific instruction can break LCSSA in any loop.
+  ///
+  /// Return true if using \p Inst just before \p NewLoc will break LCSSA,
+  /// assuming that the function containing \p Inst and \p NewLoc is currently
+  /// in LCSSA form.
+  bool usePreservesLCSSAForm(Instruction *Inst, Instruction *NewLoc) {
+    assert(Inst->getFunction() == NewLoc->getFunction() && "Can't reason about IPO!");
+    
+    auto *OldBB = Inst->getParent();
+    auto *NewBB = NewLoc->getParent();
+    
+    // Movement within the same loop does not break LCSSA (the equality check is
+    // to avoid doing a hashtable lookup in case of intra-block movement).
+    if (OldBB == NewBB)
+      return true;
+    
+    auto *OldLoop = getLoopFor(OldBB);
+    auto *NewLoop = getLoopFor(NewBB);
+    
+    return OldLoop->contains(NewLoop);
+  }
 };
 
 // Allow clients to walk the list of nested loops...
Index: lib/Analysis/ScalarEvolutionExpander.cpp
===================================================================
--- lib/Analysis/ScalarEvolutionExpander.cpp
+++ lib/Analysis/ScalarEvolutionExpander.cpp
@@ -1655,7 +1655,8 @@
       for (auto const &Ent : *Set) {
         if (Ent && isa<Instruction>(Ent) && S->getType() == Ent->getType() &&
             cast<Instruction>(Ent)->getFunction() == InsertPt->getFunction() &&
-            SE.DT.dominates(cast<Instruction>(Ent), InsertPt)) {
+            SE.DT.dominates(cast<Instruction>(Ent), InsertPt) &&
+            SE.LI.usePreservesLCSSAForm(cast<Instruction>(Ent), InsertPt)) {
           V = Ent;
           break;
         }