Index: lib/Transforms/Scalar/GVN.cpp
===================================================================
--- lib/Transforms/Scalar/GVN.cpp
+++ lib/Transforms/Scalar/GVN.cpp
@@ -1328,12 +1328,14 @@
   }
 
   // If this load follows a GEP, see if we can PRE the indices before analyzing.
-  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0))) {
-    for (GetElementPtrInst::op_iterator OI = GEP->idx_begin(),
-                                        OE = GEP->idx_end();
-         OI != OE; ++OI)
-      if (Instruction *I = dyn_cast<Instruction>(OI->get()))
-        performScalarPRE(I);
+  if (EnablePRE) {
+    if (auto GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0))) {
+      for (GetElementPtrInst::op_iterator OI = GEP->idx_begin(),
+                                          OE = GEP->idx_end();
+           OI != OE; ++OI)
+        if (Instruction *I = dyn_cast<Instruction>(OI->get()))
+          performScalarPRE(I);
+    }
   }
 
   // Step 2: Analyze the availability of the load
@@ -2143,6 +2145,7 @@
 }
 
 bool GVN::performScalarPRE(Instruction *CurInst) {
+  assert(EnablePRE && "GVN: Calling performScalarPRE with -enable-pre=false.");
   if (isa<AllocaInst>(CurInst) || CurInst->isTerminator() ||
       isa<PHINode>(CurInst) || CurInst->getType()->isVoidTy() ||
       CurInst->mayReadFromMemory() || CurInst->mayHaveSideEffects() ||
Index: test/Transforms/GVN/nonescaping-malloc.ll
===================================================================
--- test/Transforms/GVN/nonescaping-malloc.ll
+++ test/Transforms/GVN/nonescaping-malloc.ll
@@ -2,6 +2,10 @@
 ; RUN: opt < %s -basicaa -gvn -stats -disable-output 2>&1 | FileCheck %s
 ; rdar://7363102
 
+; Sanity check that GVN::performScalarPRE is not called with
+; enable-pre=false (asserts)
+; RUN: opt < %s -basicaa -gvn -enable-pre=false -disable-output 2>&1
+
 ; CHECK: Number of loads deleted
 
 ; GVN should be able to eliminate load %tmp22.i, because it is redundant with