Index: llvm/include/llvm/Transforms/IPO/PassManagerBuilder.h
===================================================================
--- llvm/include/llvm/Transforms/IPO/PassManagerBuilder.h
+++ llvm/include/llvm/Transforms/IPO/PassManagerBuilder.h
@@ -159,7 +159,6 @@
   bool LoopsInterleaved;
   bool RerollLoops;
   bool NewGVN;
-  bool DisableGVNLoadPRE;
   bool ForgetAllSCEVInLoopUnroll;
   bool VerifyInput;
   bool VerifyOutput;
Index: llvm/include/llvm/Transforms/Scalar/GVN.h
===================================================================
--- llvm/include/llvm/Transforms/Scalar/GVN.h
+++ llvm/include/llvm/Transforms/Scalar/GVN.h
@@ -76,6 +76,7 @@
   Optional<bool> AllowLoadInLoopPRE = None;
   Optional<bool> AllowLoadPRESplitBackedge = None;
   Optional<bool> AllowMemDep = None;
+  Optional<bool> AllowMemorySSA = None;
 
   GVNOptions() = default;
 
@@ -107,6 +108,12 @@
     AllowMemDep = MemDep;
     return *this;
   }
+
+  /// Enables or disables use of MemorySSA.
+  GVNOptions &setMemorySSA(bool MemSSA) {
+    AllowMemorySSA = MemSSA;
+    return *this;
+  }
 };
 
 /// The core GVN pass object.
@@ -143,6 +150,7 @@
   bool isLoadInLoopPREEnabled() const;
   bool isLoadPRESplitBackedgeEnabled() const;
   bool isMemDepEnabled() const;
+  bool isMemorySSAEnabled() const;
 
   /// This class holds the mapping between values and value numbers.  It is used
   /// as an efficient mechanism to determine the expression-wise equivalence of
@@ -367,9 +375,8 @@
   void assignBlockRPONumber(Function &F);
 };
 
-/// Create a legacy GVN pass. This also allows parameterizing whether or not
-/// MemDep is enabled.
-FunctionPass *createGVNPass(bool NoMemDepAnalysis = false);
+/// Create a legacy GVN pass.
+FunctionPass *createGVNPass();
 
 /// A simple and fast domtree-based GVN pass to hoist common expressions
 /// from sibling branches.
Index: llvm/lib/Passes/PassBuilder.cpp
===================================================================
--- llvm/lib/Passes/PassBuilder.cpp
+++ llvm/lib/Passes/PassBuilder.cpp
@@ -821,6 +821,8 @@
       Result.setLoadPRESplitBackedge(Enable);
     } else if (ParamName == "memdep") {
       Result.setMemDep(Enable);
+    } else if (ParamName == "memoryssa") {
+      Result.setMemorySSA(Enable);
     } else {
       return make_error<StringError>(
           formatv("invalid GVN pass parameter '{0}' ", ParamName).str(),
Index: llvm/lib/Passes/PassRegistry.def
===================================================================
--- llvm/lib/Passes/PassRegistry.def
+++ llvm/lib/Passes/PassRegistry.def
@@ -466,7 +466,8 @@
                           "no-pre;pre;"
                           "no-load-pre;load-pre;"
                           "no-split-backedge-load-pre;split-backedge-load-pre;"
-                          "no-memdep;memdep")
+                          "no-memdep;memdep;"
+                          "no-memoryssa;memoryssa")
 FUNCTION_PASS_WITH_PARAMS("print<stack-lifetime>",
                           "StackLifetimePrinterPass",
                            [](StackLifetime::LivenessType Type) {
Index: llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
===================================================================
--- llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -187,7 +187,6 @@
     NewGVN = RunNewGVN;
     LicmMssaOptCap = SetLicmMssaOptCap;
     LicmMssaNoAccForPromotionCap = SetLicmMssaNoAccForPromotionCap;
-    DisableGVNLoadPRE = false;
     ForgetAllSCEVInLoopUnroll = ForgetSCEVInLoopUnroll;
     VerifyInput = false;
     VerifyOutput = false;
@@ -426,7 +425,7 @@
   if (OptLevel > 1) {
     MPM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds
     MPM.add(NewGVN ? createNewGVNPass()
-                   : createGVNPass(DisableGVNLoadPRE)); // Remove redundancies
+                   : createGVNPass()); // Remove redundancies
   }
   MPM.add(createSCCPPass());                  // Constant prop with SCCP
 
@@ -1021,9 +1020,8 @@
 
   PM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap,
                         /*AllowSpeculation=*/true));
-  PM.add(NewGVN ? createNewGVNPass()
-                : createGVNPass(DisableGVNLoadPRE)); // Remove redundancies.
-  PM.add(createMemCpyOptPass());            // Remove dead memcpys.
+  PM.add(NewGVN ? createNewGVNPass() : createGVNPass()); // Remove redundancies.
+  PM.add(createMemCpyOptPass());                         // Remove dead memcpys.
 
   // Nuke dead stores.
   PM.add(createDeadStoreEliminationPass());
Index: llvm/lib/Transforms/Scalar/GVN.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/GVN.cpp
+++ llvm/lib/Transforms/Scalar/GVN.cpp
@@ -109,6 +109,7 @@
 GVNEnableSplitBackedgeInLoadPRE("enable-split-backedge-in-load-pre",
                                 cl::init(false));
 static cl::opt<bool> GVNEnableMemDep("enable-gvn-memdep", cl::init(true));
+static cl::opt<bool> GVNEnableMemorySSA("enable-gvn-memoryssa", cl::init(false));
 
 static cl::opt<uint32_t> MaxNumDeps(
     "gvn-max-num-deps", cl::Hidden, cl::init(100),
@@ -713,6 +714,10 @@
   return Options.AllowMemDep.value_or(GVNEnableMemDep);
 }
 
+bool GVNPass::isMemorySSAEnabled() const {
+  return Options.AllowMemorySSA.getValueOr(GVNEnableMemorySSA);
+}
+
 PreservedAnalyses GVNPass::run(Function &F, FunctionAnalysisManager &AM) {
   // FIXME: The order of evaluation of these 'getResult' calls is very
   // significant! Re-ordering these variables will cause GVN when run alone to
@@ -725,7 +730,8 @@
   auto *MemDep =
       isMemDepEnabled() ? &AM.getResult<MemoryDependenceAnalysis>(F) : nullptr;
   auto *LI = AM.getCachedResult<LoopAnalysis>(F);
-  auto *MSSA = AM.getCachedResult<MemorySSAAnalysis>(F);
+  auto *MSSA =
+      isMemorySSAEnabled() ? &AM.getResult<MemorySSAAnalysis>(F) : nullptr;
   auto &ORE = AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
   bool Changed = runImpl(F, AC, DT, TLI, AA, MemDep, LI, &ORE,
                          MSSA ? &MSSA->getMSSA() : nullptr);
@@ -755,7 +761,9 @@
     OS << (Options.AllowLoadPRESplitBackedge.getValue() ? "" : "no-")
        << "split-backedge-load-pre;";
   if (Options.AllowMemDep != None)
-    OS << (Options.AllowMemDep.getValue() ? "" : "no-") << "memdep";
+    OS << (Options.AllowMemDep.getValue() ? "" : "no-") << "memdep;";
+  if (Options.AllowMemorySSA != None)
+    OS << (Options.AllowMemorySSA.getValue() ? "" : "no-") << "memoryssa";
   OS << ">";
 }
 
@@ -3186,8 +3194,11 @@
 public:
   static char ID; // Pass identification, replacement for typeid
 
-  explicit GVNLegacyPass(bool NoMemDepAnalysis = !GVNEnableMemDep)
-      : FunctionPass(ID), Impl(GVNOptions().setMemDep(!NoMemDepAnalysis)) {
+  explicit GVNLegacyPass(bool MemDepAnalysis = GVNEnableMemDep,
+                         bool MemSSAAnalysis = GVNEnableMemorySSA)
+      : FunctionPass(ID), Impl(GVNOptions()
+                                   .setMemDep(MemDepAnalysis)
+                                   .setMemorySSA(MemSSAAnalysis)) {
     initializeGVNLegacyPassPass(*PassRegistry::getPassRegistry());
   }
 
@@ -3218,6 +3229,8 @@
     AU.addRequired<LoopInfoWrapperPass>();
     if (Impl.isMemDepEnabled())
       AU.addRequired<MemoryDependenceWrapperPass>();
+    if (Impl.isMemorySSAEnabled())
+      AU.addRequired<MemorySSAWrapperPass>();
     AU.addRequired<AAResultsWrapperPass>();
     AU.addPreserved<DominatorTreeWrapperPass>();
     AU.addPreserved<GlobalsAAWrapperPass>();
@@ -3235,6 +3248,7 @@
 
 INITIALIZE_PASS_BEGIN(GVNLegacyPass, "gvn", "Global Value Numbering", false, false)
 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(MemoryDependenceWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
@@ -3244,6 +3258,4 @@
 INITIALIZE_PASS_END(GVNLegacyPass, "gvn", "Global Value Numbering", false, false)
 
 // The public interface to this file...
-FunctionPass *llvm::createGVNPass(bool NoMemDepAnalysis) {
-  return new GVNLegacyPass(NoMemDepAnalysis);
-}
+FunctionPass *llvm::createGVNPass() { return new GVNLegacyPass(); }
Index: llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
+++ llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
@@ -9,7 +9,7 @@
 ; RUN:   | grep -v 'Verify generated machine code' | FileCheck -match-full-lines -strict-whitespace -check-prefix=GCN-O1-OPTS %s
 ; RUN: llc -O2 -mtriple=amdgcn--amdhsa -disable-verify -debug-pass=Structure < %s 2>&1 \
 ; RUN:   | grep -v 'Verify generated machine code' | FileCheck -match-full-lines -strict-whitespace -check-prefix=GCN-O2 %s
-; RUN: llc -O3 -mtriple=amdgcn--amdhsa -disable-verify -debug-pass=Structure < %s 2>&1 \
+; RUN: llc -O3 -mtriple=amdgcn--amdhsa -disable-verify -debug-pass=Structure -enable-gvn-memoryssa=false < %s 2>&1 \
 ; RUN:   | grep -v 'Verify generated machine code' | FileCheck -match-full-lines -strict-whitespace -check-prefix=GCN-O3 %s
 
 ; REQUIRES: asserts
Index: llvm/test/Other/new-pm-print-pipeline.ll
===================================================================
--- llvm/test/Other/new-pm-print-pipeline.ll
+++ llvm/test/Other/new-pm-print-pipeline.ll
@@ -34,8 +34,8 @@
 ; RUN: opt -disable-output -disable-verify -print-pipeline-passes -passes='function(loop-unroll<>,loop-unroll<partial;peeling;runtime;upperbound;profile-peeling;full-unroll-max=5;O1>,loop-unroll<no-partial;no-peeling;no-runtime;no-upperbound;no-profile-peeling;full-unroll-max=7;O1>)' < %s | FileCheck %s --match-full-lines --check-prefixes=CHECK-10
 ; CHECK-10: function(loop-unroll<O2>,loop-unroll<partial;peeling;runtime;upperbound;profile-peeling;full-unroll-max=5;O1>,loop-unroll<no-partial;no-peeling;no-runtime;no-upperbound;no-profile-peeling;full-unroll-max=7;O1>)
 
-; RUN: opt -disable-output -disable-verify -print-pipeline-passes -passes='function(gvn<>,gvn<pre;load-pre;split-backedge-load-pre;memdep>,gvn<no-pre;no-load-pre;no-split-backedge-load-pre;no-memdep>)' < %s | FileCheck %s --match-full-lines --check-prefixes=CHECK-11
-; CHECK-11: function(gvn<>,gvn<pre;load-pre;split-backedge-load-pre;memdep>,gvn<no-pre;no-load-pre;no-split-backedge-load-pre;no-memdep>)
+; RUN: opt -disable-output -disable-verify -print-pipeline-passes -passes='function(gvn<>,gvn<pre;load-pre;split-backedge-load-pre;memdep;memoryssa>,gvn<no-pre;no-load-pre;no-split-backedge-load-pre;no-memdep;no-memoryssa>)' < %s | FileCheck %s --match-full-lines --check-prefixes=CHECK-11
+; CHECK-11: function(gvn<>,gvn<pre;load-pre;split-backedge-load-pre;memdep;memoryssa>,gvn<no-pre;no-load-pre;no-split-backedge-load-pre;no-memdep;no-memoryssa>)
 
 ; RUN: opt -disable-output -disable-verify -print-pipeline-passes -passes='function(early-cse<>,early-cse<memssa>)' < %s | FileCheck %s --match-full-lines --check-prefixes=CHECK-12
 ; CHECK-12: function(early-cse<>,early-cse<memssa>)