Index: include/llvm/Transforms/Scalar/GVN.h
===================================================================
--- include/llvm/Transforms/Scalar/GVN.h
+++ include/llvm/Transforms/Scalar/GVN.h
@@ -274,7 +274,8 @@
                                  BasicBlock *Curr, unsigned int ValNo);
   Value *findLeader(const BasicBlock *BB, uint32_t num);
   void cleanupGlobalSets();
-  void fillImplicitControlFlowInfo(ReversePostOrderTraversal<Function *> &RPOT);
+  void fillImplicitControlFlowInfo(BasicBlock *BB);
+  bool isFirstImplicitControlFlowInstruction(Instruction *I);
   void verifyRemoved(const Instruction *I) const;
   bool splitCriticalEdges();
   BasicBlock *splitCriticalEdges(BasicBlock *Pred, BasicBlock *Succ);
Index: lib/Transforms/Scalar/GVN.cpp
===================================================================
--- lib/Transforms/Scalar/GVN.cpp
+++ lib/Transforms/Scalar/GVN.cpp
@@ -1199,7 +1199,11 @@
     while (!NewInsts.empty()) {
       Instruction *I = NewInsts.pop_back_val();
       if (MD) MD->removeInstruction(I);
+      BasicBlock *IBB = I->getParent();
+      bool IsFirstImplicitCF = isFirstImplicitControlFlowInstruction(I);
       I->eraseFromParent();
+      if (IsFirstImplicitCF)
+        fillImplicitControlFlowInfo(IBB);
     }
     // HINT: Don't revert the edge-splitting as following transformation may
     // also need to split these critical edges.
@@ -2099,7 +2103,11 @@
       DEBUG(dbgs() << "GVN removed: " << **I << '\n');
       if (MD) MD->removeInstruction(*I);
       DEBUG(verifyRemoved(*I));
+      BasicBlock *IBB = (*I)->getParent();
+      bool IsFirstImplicitCF = isFirstImplicitControlFlowInstruction(*I);
       (*I)->eraseFromParent();
+      if (IsFirstImplicitCF)
+        fillImplicitControlFlowInfo(IBB);
     }
 
     if (!InstrsToErase.empty())
@@ -2298,7 +2306,11 @@
   if (MD)
     MD->removeInstruction(CurInst);
   DEBUG(verifyRemoved(CurInst));
+
+  bool IsFirstImplicitCF = isFirstImplicitControlFlowInstruction(CurInst);
   CurInst->eraseFromParent();
+  if (IsFirstImplicitCF)
+    fillImplicitControlFlowInfo(CurrentBlock);
   OI->invalidateBlock(CurrentBlock);
   ++NumGVNInstr;
 
@@ -2366,7 +2378,9 @@
   // RPOT walks the graph in its constructor and will not be invalidated during
   // processBlock.
   ReversePostOrderTraversal<Function *> RPOT(&F);
-  fillImplicitControlFlowInfo(RPOT);
+
+  for (BasicBlock *BB : RPOT)
+    fillImplicitControlFlowInfo(BB);
   for (BasicBlock *BB : RPOT)
     Changed |= processBlock(BB);
 
@@ -2382,7 +2396,7 @@
 }
 
 void
-GVN::fillImplicitControlFlowInfo(ReversePostOrderTraversal<Function *> &RPOT) {
+GVN::fillImplicitControlFlowInfo(BasicBlock *BB) {
   auto MayNotTransferExecutionToSuccessor = [&](const Instruction *I) {
     // If a block's instruction doesn't always pass the control to its successor
     // instruction, mark the block as having implicit control flow. We use them
@@ -2410,13 +2424,21 @@
     }
     return true;
   };
+  FirstImplicitControlFlowInsts.erase(BB);
 
-  for (BasicBlock *BB : RPOT)
-    for (auto &I : *BB)
-      if (MayNotTransferExecutionToSuccessor(&I)) {
-        FirstImplicitControlFlowInsts[BB] = &I;
-        break;
-      }
+  for (auto &I : *BB)
+    if (MayNotTransferExecutionToSuccessor(&I)) {
+      FirstImplicitControlFlowInsts[BB] = &I;
+      break;
+    }
+}
+
+bool GVN::isFirstImplicitControlFlowInstruction(Instruction *I) {
+  assert(I->getParent() && "Instruction already erased?");
+  auto It = FirstImplicitControlFlowInsts.find(I->getParent());
+  if (It == FirstImplicitControlFlowInsts.end())
+    return false;
+  return It->second == I;
 }
 
 /// Verify that the specified instruction does not occur in our
Index: test/Transforms/GVN/PRE/2017-10-16-LoadPRECrash.ll
===================================================================
--- test/Transforms/GVN/PRE/2017-10-16-LoadPRECrash.ll
+++ test/Transforms/GVN/PRE/2017-10-16-LoadPRECrash.ll
@@ -0,0 +1,31 @@
+; RUN: opt -S -gvn -enable-load-pre < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%ArrayImpl = type { i64, i64 addrspace(100)*, [1 x i64], [1 x i64], [1 x i64], i64, i64, double addrspace(100)*, double addrspace(100)*, i8, i64 }
+
+; Function Attrs: readnone
+declare %ArrayImpl* @getaddr_ArrayImpl(%ArrayImpl addrspace(100)*) #0
+
+; Function Attrs: readnone
+declare i64* @getaddr_i64(i64 addrspace(100)*) #0
+
+; Make sure that the test compiles without a crash.
+
+define hidden void @wrapon_fn173() {
+
+; CHECK-LABEL: @wrapon_fn173
+
+entry:
+  %0 = call %ArrayImpl* @getaddr_ArrayImpl(%ArrayImpl addrspace(100)* undef)
+  br label %loop
+
+loop:
+  %1 = call %ArrayImpl* @getaddr_ArrayImpl(%ArrayImpl addrspace(100)* undef)
+  %2 = load i64 addrspace(100)*, i64 addrspace(100)** null, align 8
+  %3 = call i64* @getaddr_i64(i64 addrspace(100)* %2)
+  br label %loop
+}
+
+attributes #0 = { readnone }