Index: lib/CodeGen/SafeStack.cpp
===================================================================
--- lib/CodeGen/SafeStack.cpp
+++ lib/CodeGen/SafeStack.cpp
@@ -459,6 +459,9 @@
                                 AllocaInst *StackGuardSlot, Value *StackGuard) {
   Value *V = IRB.CreateLoad(StackGuardSlot);
   Value *Cmp = IRB.CreateICmpNE(StackGuard, V);
+  PointerType *GuardPtrType = dyn_cast<PointerType>(StackGuard->getType());
+  // Zero the protector after it was checked to prohibit leaks.
+  IRB.CreateStore(ConstantPointerNull::get(GuardPtrType), StackGuardSlot, true);
 
   auto SuccessProb = BranchProbabilityInfo::getBranchProbStackProtector(true);
   auto FailureProb = BranchProbabilityInfo::getBranchProbStackProtector(false);
Index: lib/CodeGen/StackProtector.cpp
===================================================================
--- lib/CodeGen/StackProtector.cpp
+++ lib/CodeGen/StackProtector.cpp
@@ -445,6 +445,7 @@
       //     %1 = <stack guard>
       //     %2 = load StackGuardSlot
       //     %3 = cmp i1 %1, %2
+      //     store 0, StackGuardSlot
       //     br i1 %3, label %SP_return, label %CallStackCheckFailBlk
       //
       //   SP_return:
@@ -480,6 +481,9 @@
       Value *Guard = getStackGuard(TLI, M, B);
       LoadInst *LI2 = B.CreateLoad(AI, true);
       Value *Cmp = B.CreateICmpEQ(Guard, LI2);
+      PointerType *GuardPtrType = dyn_cast<PointerType>(Guard->getType());
+      // Zero the protector after it was checked to prohibit leaks.
+      B.CreateStore(ConstantPointerNull::get(GuardPtrType), AI, true);
       auto SuccessProb =
           BranchProbabilityInfo::getBranchProbStackProtector(true);
       auto FailureProb =