diff --git a/include/llvm/Analysis/MemoryDependenceAnalysis.h b/include/llvm/Analysis/MemoryDependenceAnalysis.h
index 01d060f30c8..a8ce34b5ee5 100644
--- a/include/llvm/Analysis/MemoryDependenceAnalysis.h
+++ b/include/llvm/Analysis/MemoryDependenceAnalysis.h
@@ -350,6 +350,11 @@ public:
                           DominatorTree &DT)
       : AA(AA), AC(AC), TLI(TLI), DT(DT) {}
 
+  /// Some methods limit the number of instructions they will examine.
+  /// The return value of this method is the default limit that will be
+  /// used if no limit is explicitly passed in.
+  unsigned getDefaultBlockScanLimit() const;
+
   /// Returns the instruction on which a memory operation depends.
   ///
   /// See the class comment for more details.  It is illegal to call this on
@@ -409,19 +414,25 @@ public:
   /// operations.  If isLoad is false, this routine ignores may-aliases
   /// with reads from read-only locations. If possible, pass the query
   /// instruction as well; this function may take advantage of the metadata
-  /// annotated to the query instruction to refine the result.
+  /// annotated to the query instruction to refine the result. \p Limit
+  /// can be used to set the maximum number of instructions that will be
+  /// examined to find the pointer dependency. On return, it will be set to
+  /// the number of instructions left to examine. If a null pointer is passed
+  /// in, the limit will default to the value of -memdep-block-scan-limit.
   ///
   /// Note that this is an uncached query, and thus may be inefficient.
   MemDepResult getPointerDependencyFrom(const MemoryLocation &Loc, bool isLoad,
                                         BasicBlock::iterator ScanIt,
                                         BasicBlock *BB,
-                                        Instruction *QueryInst = nullptr);
+                                        Instruction *QueryInst = nullptr,
+                                        unsigned *Limit = nullptr);
 
   MemDepResult getSimplePointerDependencyFrom(const MemoryLocation &MemLoc,
                                               bool isLoad,
                                               BasicBlock::iterator ScanIt,
                                               BasicBlock *BB,
-                                              Instruction *QueryInst);
+                                              Instruction *QueryInst,
+                                              unsigned *Limit = nullptr);
 
   /// This analysis looks for other loads and stores with invariant.group
   /// metadata and the same pointer operand. Returns Unknown if it does not
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index 91e627c1006..fe0f6a2d261 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -341,7 +341,7 @@ static bool isVolatile(Instruction *Inst) {
 
 MemDepResult MemoryDependenceResults::getPointerDependencyFrom(
     const MemoryLocation &MemLoc, bool isLoad, BasicBlock::iterator ScanIt,
-    BasicBlock *BB, Instruction *QueryInst) {
+    BasicBlock *BB, Instruction *QueryInst, unsigned *Limit) {
 
   if (QueryInst != nullptr) {
     if (auto *LI = dyn_cast<LoadInst>(QueryInst)) {
@@ -352,7 +352,8 @@ MemDepResult MemoryDependenceResults::getPointerDependencyFrom(
         return invariantGroupDependency;
     }
   }
-  return getSimplePointerDependencyFrom(MemLoc, isLoad, ScanIt, BB, QueryInst);
+  return getSimplePointerDependencyFrom(MemLoc, isLoad, ScanIt, BB, QueryInst,
+                                        Limit);
 }
 
 MemDepResult
@@ -408,12 +409,18 @@ MemoryDependenceResults::getInvariantGroupPointerDependency(LoadInst *LI,
 
 MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
     const MemoryLocation &MemLoc, bool isLoad, BasicBlock::iterator ScanIt,
-    BasicBlock *BB, Instruction *QueryInst) {
+    BasicBlock *BB, Instruction *QueryInst, unsigned *Limit) {
+
   const Value *MemLocBase = nullptr;
   int64_t MemLocOffset = 0;
-  unsigned Limit = BlockScanLimit;
   bool isInvariantLoad = false;
 
+  if (!Limit) {
+    unsigned DefaultLimit = BlockScanLimit;
+    return getSimplePointerDependencyFrom(MemLoc, isLoad, ScanIt, BB, QueryInst,
+                                          &DefaultLimit);
+  }
+
   // We must be careful with atomic accesses, as they may allow another thread
   //   to touch this location, clobbering it. We are conservative: if the
   //   QueryInst is not a simple (non-atomic) memory access, we automatically
@@ -487,8 +494,8 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
 
     // Limit the amount of scanning we do so we don't end up with quadratic
     // running time on extreme testcases.
-    --Limit;
-    if (!Limit)
+    --*Limit;
+    if (!*Limit)
       return MemDepResult::getUnknown();
 
     if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
@@ -1712,6 +1719,10 @@ void MemoryDependenceWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
 }
 
+unsigned MemoryDependenceResults::getDefaultBlockScanLimit() const {
+  return BlockScanLimit;
+}
+
 bool MemoryDependenceWrapperPass::runOnFunction(Function &F) {
   auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
   auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp
index fbe2726bed7..4d4c3baef3f 100644
--- a/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -1050,6 +1050,13 @@ static bool eliminateDeadStores(BasicBlock &BB, AliasAnalysis *AA,
     if (!Loc.Ptr)
       continue;
 
+    // Loop until we find a store we can eliminate or a load that
+    // invalidates the analysis. Without an upper bound on the number of
+    // instructions examined, this analysis can become very time-consuming.
+    // However, the potential gain diminishes as we process more instructions
+    // without eliminating any of them. Therefore, we limit the number of
+    // instructions we look at.
+    auto Limit = MD->getDefaultBlockScanLimit();
     while (InstDep.isDef() || InstDep.isClobber()) {
       // Get the memory clobbered by the instruction we depend on.  MemDep will
       // skip any instructions that 'Loc' clearly doesn't interact with.  If we
@@ -1138,8 +1145,9 @@ static bool eliminateDeadStores(BasicBlock &BB, AliasAnalysis *AA,
       if (AA->getModRefInfo(DepWrite, Loc) & MRI_Ref)
         break;
 
-      InstDep = MD->getPointerDependencyFrom(Loc, false,
-                                             DepWrite->getIterator(), &BB);
+      InstDep = MD->getPointerDependencyFrom(Loc, /*isLoad=*/ false,
+                                             DepWrite->getIterator(), &BB,
+                                             /*QueryInst=*/ nullptr, &Limit);
     }
   }