diff --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -1102,7 +1102,7 @@
     return I.first->second;
   }
 
-  Optional<MemoryLocation> getLocForWriteEx(Instruction *I) const {
+  Optional<MemoryLocation> getLocForWriteEx(Instruction *I) {
     if (!I->mayWriteToMemory())
       return None;
 
@@ -1358,6 +1358,7 @@
     Instruction *KillingI = KillingDef->getMemoryInst();
     LLVM_DEBUG(dbgs() << "  trying to get dominating access\n");
 
+    bool CanOptimize = KillingDef->getDefiningAccess() == StartAccess;
     // Find the next clobbering Mod access for DefLoc, starting at StartAccess.
     Optional<MemoryLocation> CurrentLoc;
     for (;; Current = cast<MemoryDef>(Current)->getDefiningAccess()) {
@@ -1399,8 +1400,11 @@
       Instruction *CurrentI = CurrentDef->getMemoryInst();
 
       if (canSkipDef(CurrentDef, !isInvisibleToCallerBeforeRet(KillingUndObj),
-                     TLI))
+                     TLI)) {
+
+        CanOptimize &= !isa<FenceInst>(CurrentDef->getMemoryInst());
         continue;
+      }
 
       // Before we try to remove anything, check for any extra throwing
       // instructions that block us from DSEing
@@ -1436,13 +1440,17 @@
 
       // If Current cannot be analyzed or is not removable, check the next
       // candidate.
-      if (!hasAnalyzableMemoryWrite(CurrentI, TLI) || !isRemovable(CurrentI))
+      if (!hasAnalyzableMemoryWrite(CurrentI, TLI) || !isRemovable(CurrentI)) {
+        CanOptimize = false;
         continue;
+      }
 
       // If Current does not have an analyzable write location, skip it
       CurrentLoc = getLocForWriteEx(CurrentI);
-      if (!CurrentLoc)
+      if (!CurrentLoc) {
+        CanOptimize = false;
         continue;
+      }
 
       // AliasAnalysis does not account for loops. Limit elimination to
       // candidates for which we can guarantee they always store to the same
@@ -1450,6 +1458,7 @@
       if (!isGuaranteedLoopIndependent(CurrentI, KillingI, *CurrentLoc)) {
         LLVM_DEBUG(dbgs() << "  ... not guaranteed loop independent\n");
         WalkerStepLimit -= 1;
+        CanOptimize = false;
         continue;
       }
 
@@ -1457,13 +1466,23 @@
         // If the killing def is a memory terminator (e.g. lifetime.end), check
         // the next candidate if the current Current does not write the same
         // underlying object as the terminator.
-        if (!isMemTerminator(*CurrentLoc, CurrentI, KillingI))
+        if (!isMemTerminator(*CurrentLoc, CurrentI, KillingI)) {
+          CanOptimize = false;
           continue;
+        }
       } else {
         int64_t KillingOffset = 0;
         int64_t DeadOffset = 0;
         auto OR = isOverwrite(KillingI, CurrentI, KillingLoc, *CurrentLoc,
                               KillingOffset, DeadOffset);
+        if (CanOptimize) {
+          if (OR == OW_Complete || OR == OW_MaybePartial)
+            KillingDef->setOptimized(CurrentDef);
+          if (OR != OW_None) {
+            CanOptimize = false;
+          }
+        }
+
         // If Current does not write to the same object as KillingDef, check
         // the next candidate.
         if (OR == OW_Unknown || OR == OW_None)