diff --git a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
--- a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -67,6 +67,11 @@
 
 #define DEBUG_TYPE "memcpyopt"
 
+// TODO: Actually implement MemorySSA-based MemCpyOpt.
+static cl::opt<bool>
+    EnableMemorySSA("enable-memcpyopt-memoryssa", cl::init(false), cl::Hidden,
+                    cl::desc("Use MemorySSA-backed MemCpyOpt."));
+
 STATISTIC(NumMemCpyInstr, "Number of memcpy instructions deleted");
 STATISTIC(NumMemSetInfer, "Number of memsets inferred");
 STATISTIC(NumMoveToCpy,   "Number of memmoves converted to memcpy");
@@ -282,6 +287,8 @@
     AU.addPreserved<MemoryDependenceWrapperPass>();
     AU.addRequired<AAResultsWrapperPass>();
     AU.addPreserved<AAResultsWrapperPass>();
+    if (EnableMemorySSA)
+      AU.addRequired<MemorySSAWrapperPass>();
     AU.addPreserved<MemorySSAWrapperPass>();
   }
 };
@@ -1477,7 +1484,8 @@
   auto *AA = &AM.getResult<AAManager>(F);
   auto *AC = &AM.getResult<AssumptionAnalysis>(F);
   auto *DT = &AM.getResult<DominatorTreeAnalysis>(F);
-  auto *MSSA = AM.getCachedResult<MemorySSAAnalysis>(F);
+  auto *MSSA = EnableMemorySSA ? &AM.getResult<MemorySSAAnalysis>(F)
+                               : AM.getCachedResult<MemorySSAAnalysis>(F);
 
   bool MadeChange =
       runImpl(F, &MD, &TLI, AA, AC, DT, MSSA ? &MSSA->getMSSA() : nullptr);
@@ -1534,7 +1542,9 @@
   auto *AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
   auto *AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
   auto *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
-  auto *MSSAWP = getAnalysisIfAvailable<MemorySSAWrapperPass>();
+  auto *MSSAWP = EnableMemorySSA
+      ? &getAnalysis<MemorySSAWrapperPass>()
+      : getAnalysisIfAvailable<MemorySSAWrapperPass>();
 
   return Impl.runImpl(F, MD, TLI, AA, AC, DT,
                       MSSAWP ? &MSSAWP->getMSSA() : nullptr);
diff --git a/llvm/test/Transforms/MemCpyOpt/2008-02-24-MultipleUseofSRet.ll b/llvm/test/Transforms/MemCpyOpt/2008-02-24-MultipleUseofSRet.ll
--- a/llvm/test/Transforms/MemCpyOpt/2008-02-24-MultipleUseofSRet.ll
+++ b/llvm/test/Transforms/MemCpyOpt/2008-02-24-MultipleUseofSRet.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -basic-aa -memcpyopt -dse -S | FileCheck %s
+; RUN: opt < %s -basic-aa -memcpyopt -dse -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -basic-aa -memcpyopt -dse -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 ; PR2077
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
diff --git a/llvm/test/Transforms/MemCpyOpt/2008-03-13-ReturnSlotBitcast.ll b/llvm/test/Transforms/MemCpyOpt/2008-03-13-ReturnSlotBitcast.ll
--- a/llvm/test/Transforms/MemCpyOpt/2008-03-13-ReturnSlotBitcast.ll
+++ b/llvm/test/Transforms/MemCpyOpt/2008-03-13-ReturnSlotBitcast.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -basic-aa -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64"
 
 %a = type { i32 }
diff --git a/llvm/test/Transforms/MemCpyOpt/2011-06-02-CallSlotOverwritten.ll b/llvm/test/Transforms/MemCpyOpt/2011-06-02-CallSlotOverwritten.ll
--- a/llvm/test/Transforms/MemCpyOpt/2011-06-02-CallSlotOverwritten.ll
+++ b/llvm/test/Transforms/MemCpyOpt/2011-06-02-CallSlotOverwritten.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -basic-aa -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 ; PR10067
 ; Make sure the call+copy isn't optimized in such a way that
 ; %ret ends up with the wrong value.
diff --git a/llvm/test/Transforms/MemCpyOpt/aggregate-type-crash.ll b/llvm/test/Transforms/MemCpyOpt/aggregate-type-crash.ll
--- a/llvm/test/Transforms/MemCpyOpt/aggregate-type-crash.ll
+++ b/llvm/test/Transforms/MemCpyOpt/aggregate-type-crash.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -memcpyopt -S -o - < %s | FileCheck %s
+; RUN: opt -memcpyopt -S -o - < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -memcpyopt -S -o - < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.14.0"
diff --git a/llvm/test/Transforms/MemCpyOpt/align.ll b/llvm/test/Transforms/MemCpyOpt/align.ll
--- a/llvm/test/Transforms/MemCpyOpt/align.ll
+++ b/llvm/test/Transforms/MemCpyOpt/align.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -S -basic-aa -memcpyopt | FileCheck %s
+; RUN: opt < %s -S -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -S -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64"
 
 declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i1) nounwind
diff --git a/llvm/test/Transforms/MemCpyOpt/atomic.ll b/llvm/test/Transforms/MemCpyOpt/atomic.ll
--- a/llvm/test/Transforms/MemCpyOpt/atomic.ll
+++ b/llvm/test/Transforms/MemCpyOpt/atomic.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -basic-aa -memcpyopt -S < %s | FileCheck %s
+; RUN: opt -basic-aa -memcpyopt -S < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -basic-aa -memcpyopt -S < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 target triple = "x86_64-apple-macosx10.7.0"
diff --git a/llvm/test/Transforms/MemCpyOpt/callslot.ll b/llvm/test/Transforms/MemCpyOpt/callslot.ll
--- a/llvm/test/Transforms/MemCpyOpt/callslot.ll
+++ b/llvm/test/Transforms/MemCpyOpt/callslot.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -memcpyopt < %s | FileCheck %s
+; RUN: opt -S -memcpyopt < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -S -memcpyopt < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 define i8 @read_dest_between_call_and_memcpy() {
 ; CHECK-LABEL: @read_dest_between_call_and_memcpy(
diff --git a/llvm/test/Transforms/MemCpyOpt/callslot_aa.ll b/llvm/test/Transforms/MemCpyOpt/callslot_aa.ll
--- a/llvm/test/Transforms/MemCpyOpt/callslot_aa.ll
+++ b/llvm/test/Transforms/MemCpyOpt/callslot_aa.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -S -basic-aa -memcpyopt | FileCheck %s
+; RUN: opt < %s -S -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -S -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
 %T = type { i64, i64 }
diff --git a/llvm/test/Transforms/MemCpyOpt/callslot_deref.ll b/llvm/test/Transforms/MemCpyOpt/callslot_deref.ll
--- a/llvm/test/Transforms/MemCpyOpt/callslot_deref.ll
+++ b/llvm/test/Transforms/MemCpyOpt/callslot_deref.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -S -basic-aa -memcpyopt | FileCheck %s
+; RUN: opt < %s -S -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -S -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
 
 declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i1) unnamed_addr nounwind
diff --git a/llvm/test/Transforms/MemCpyOpt/callslot_throw.ll b/llvm/test/Transforms/MemCpyOpt/callslot_throw.ll
--- a/llvm/test/Transforms/MemCpyOpt/callslot_throw.ll
+++ b/llvm/test/Transforms/MemCpyOpt/callslot_throw.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -memcpyopt < %s | FileCheck %s
+; RUN: opt -S -memcpyopt < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -S -memcpyopt < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 declare void @may_throw(i32* nocapture %x)
 
 define void @test1(i32* nocapture noalias dereferenceable(4) %x) {
diff --git a/llvm/test/Transforms/MemCpyOpt/capturing-func.ll b/llvm/test/Transforms/MemCpyOpt/capturing-func.ll
--- a/llvm/test/Transforms/MemCpyOpt/capturing-func.ll
+++ b/llvm/test/Transforms/MemCpyOpt/capturing-func.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -basic-aa -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e"
 
diff --git a/llvm/test/Transforms/MemCpyOpt/crash.ll b/llvm/test/Transforms/MemCpyOpt/crash.ll
--- a/llvm/test/Transforms/MemCpyOpt/crash.ll
+++ b/llvm/test/Transforms/MemCpyOpt/crash.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -S -basic-aa -memcpyopt | FileCheck %s
+; RUN: opt < %s -S -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -S -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64"
 target triple = "armv7-eabi"
diff --git a/llvm/test/Transforms/MemCpyOpt/fca2memcpy.ll b/llvm/test/Transforms/MemCpyOpt/fca2memcpy.ll
--- a/llvm/test/Transforms/MemCpyOpt/fca2memcpy.ll
+++ b/llvm/test/Transforms/MemCpyOpt/fca2memcpy.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -memcpyopt -S < %s | FileCheck %s
+; RUN: opt -memcpyopt -S < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -memcpyopt -S < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-i64:64-f80:128-n8:16:32:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/MemCpyOpt/form-memset.ll b/llvm/test/Transforms/MemCpyOpt/form-memset.ll
--- a/llvm/test/Transforms/MemCpyOpt/form-memset.ll
+++ b/llvm/test/Transforms/MemCpyOpt/form-memset.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 ; All the stores in this example should be merged into a single memset.
 
diff --git a/llvm/test/Transforms/MemCpyOpt/invariant.start.ll b/llvm/test/Transforms/MemCpyOpt/invariant.start.ll
--- a/llvm/test/Transforms/MemCpyOpt/invariant.start.ll
+++ b/llvm/test/Transforms/MemCpyOpt/invariant.start.ll
@@ -1,6 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; MemCpy optimizations should take place even in presence of invariant.start
-; RUN: opt < %s -basic-aa -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
 
diff --git a/llvm/test/Transforms/MemCpyOpt/lifetime.ll b/llvm/test/Transforms/MemCpyOpt/lifetime.ll
--- a/llvm/test/Transforms/MemCpyOpt/lifetime.ll
+++ b/llvm/test/Transforms/MemCpyOpt/lifetime.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -O2 -S | FileCheck %s
+; RUN: opt < %s -O2 -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -O2 -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 ; performCallSlotOptzn in MemCpy should not exchange the calls to
 ; @llvm.lifetime.start and @llvm.memcpy.
diff --git a/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll b/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll
--- a/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll
+++ b/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -basic-aa -scoped-noalias-aa -memcpyopt -S %s | FileCheck %s
+; RUN: opt -basic-aa -scoped-noalias-aa -memcpyopt -S %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -basic-aa -scoped-noalias-aa -memcpyopt -S %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 %T = type { i8, i32 }
 
diff --git a/llvm/test/Transforms/MemCpyOpt/loadstore-sret.ll b/llvm/test/Transforms/MemCpyOpt/loadstore-sret.ll
--- a/llvm/test/Transforms/MemCpyOpt/loadstore-sret.ll
+++ b/llvm/test/Transforms/MemCpyOpt/loadstore-sret.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S < %s -basic-aa -memcpyopt | FileCheck %s
+; RUN: opt -S < %s -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -S < %s -basic-aa -memcpyopt -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 ; <rdar://problem/8536696>
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
diff --git a/llvm/test/Transforms/MemCpyOpt/memcpy-invoke-memcpy.ll b/llvm/test/Transforms/MemCpyOpt/memcpy-invoke-memcpy.ll
--- a/llvm/test/Transforms/MemCpyOpt/memcpy-invoke-memcpy.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memcpy-invoke-memcpy.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 ; Test memcpy-memcpy dependencies across invoke edges.
 
diff --git a/llvm/test/Transforms/MemCpyOpt/memcpy-to-memset-with-lifetimes.ll b/llvm/test/Transforms/MemCpyOpt/memcpy-to-memset-with-lifetimes.ll
--- a/llvm/test/Transforms/MemCpyOpt/memcpy-to-memset-with-lifetimes.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memcpy-to-memset-with-lifetimes.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -basic-aa -memcpyopt -instcombine -S < %s | FileCheck %s
+; RUN: opt -basic-aa -memcpyopt -instcombine -S < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -basic-aa -memcpyopt -instcombine -S < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/MemCpyOpt/memcpy-to-memset.ll b/llvm/test/Transforms/MemCpyOpt/memcpy-to-memset.ll
--- a/llvm/test/Transforms/MemCpyOpt/memcpy-to-memset.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memcpy-to-memset.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -memcpyopt -S < %s | FileCheck %s
+; RUN: opt -memcpyopt -S < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -memcpyopt -S < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i1) nounwind
 
diff --git a/llvm/test/Transforms/MemCpyOpt/memcpy-undef.ll b/llvm/test/Transforms/MemCpyOpt/memcpy-undef.ll
--- a/llvm/test/Transforms/MemCpyOpt/memcpy-undef.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memcpy-undef.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -basic-aa -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.8.0"
diff --git a/llvm/test/Transforms/MemCpyOpt/memcpy.ll b/llvm/test/Transforms/MemCpyOpt/memcpy.ll
--- a/llvm/test/Transforms/MemCpyOpt/memcpy.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memcpy.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -basic-aa -memcpyopt -dse -S | FileCheck %s
+; RUN: opt < %s -basic-aa -memcpyopt -dse -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -basic-aa -memcpyopt -dse -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
 target triple = "i686-apple-darwin9"
diff --git a/llvm/test/Transforms/MemCpyOpt/memmove.ll b/llvm/test/Transforms/MemCpyOpt/memmove.ll
--- a/llvm/test/Transforms/MemCpyOpt/memmove.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memmove.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -basic-aa -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 ; These memmoves should get optimized to memcpys.
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
diff --git a/llvm/test/Transforms/MemCpyOpt/memset-memcpy-oversized.ll b/llvm/test/Transforms/MemCpyOpt/memset-memcpy-oversized.ll
--- a/llvm/test/Transforms/MemCpyOpt/memset-memcpy-oversized.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memset-memcpy-oversized.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -memcpyopt -S %s | FileCheck %s
+; RUN: opt -memcpyopt -S %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -memcpyopt -S %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 ; memset -> memcpy forwarding, if memcpy is larger than memset, but trailing
 ; bytes are known to be undef.
diff --git a/llvm/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll b/llvm/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll
--- a/llvm/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -basic-aa -memcpyopt -S %s | FileCheck %s
+; RUN: opt -basic-aa -memcpyopt -S %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -basic-aa -memcpyopt -S %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 
diff --git a/llvm/test/Transforms/MemCpyOpt/memset-memcpy-to-2x-memset.ll b/llvm/test/Transforms/MemCpyOpt/memset-memcpy-to-2x-memset.ll
--- a/llvm/test/Transforms/MemCpyOpt/memset-memcpy-to-2x-memset.ll
+++ b/llvm/test/Transforms/MemCpyOpt/memset-memcpy-to-2x-memset.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -memcpyopt -S %s | FileCheck %s
+; RUN: opt -memcpyopt -S %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -memcpyopt -S %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 
diff --git a/llvm/test/Transforms/MemCpyOpt/merge-into-memset.ll b/llvm/test/Transforms/MemCpyOpt/merge-into-memset.ll
--- a/llvm/test/Transforms/MemCpyOpt/merge-into-memset.ll
+++ b/llvm/test/Transforms/MemCpyOpt/merge-into-memset.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
diff --git a/llvm/test/Transforms/MemCpyOpt/mixed-sizes.ll b/llvm/test/Transforms/MemCpyOpt/mixed-sizes.ll
--- a/llvm/test/Transforms/MemCpyOpt/mixed-sizes.ll
+++ b/llvm/test/Transforms/MemCpyOpt/mixed-sizes.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 ; Handle memcpy-memcpy dependencies of differing sizes correctly.
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/llvm/test/Transforms/MemCpyOpt/non-integral.ll b/llvm/test/Transforms/MemCpyOpt/non-integral.ll
--- a/llvm/test/Transforms/MemCpyOpt/non-integral.ll
+++ b/llvm/test/Transforms/MemCpyOpt/non-integral.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -memcpyopt -S < %s | FileCheck %s
+; RUN: opt -memcpyopt -S < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -memcpyopt -S < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128-ni:1"
 
diff --git a/llvm/test/Transforms/MemCpyOpt/nonlocal-memcpy-memcpy.ll b/llvm/test/Transforms/MemCpyOpt/nonlocal-memcpy-memcpy.ll
--- a/llvm/test/Transforms/MemCpyOpt/nonlocal-memcpy-memcpy.ll
+++ b/llvm/test/Transforms/MemCpyOpt/nonlocal-memcpy-memcpy.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 ; Test whether memcpy-memcpy dependence is optimized across
 ; basic blocks (conditional branches and invokes).
diff --git a/llvm/test/Transforms/MemCpyOpt/nontemporal.ll b/llvm/test/Transforms/MemCpyOpt/nontemporal.ll
--- a/llvm/test/Transforms/MemCpyOpt/nontemporal.ll
+++ b/llvm/test/Transforms/MemCpyOpt/nontemporal.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
diff --git a/llvm/test/Transforms/MemCpyOpt/pr29105.ll b/llvm/test/Transforms/MemCpyOpt/pr29105.ll
--- a/llvm/test/Transforms/MemCpyOpt/pr29105.ll
+++ b/llvm/test/Transforms/MemCpyOpt/pr29105.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -memcpyopt -instcombine -S %s | FileCheck %s
+; RUN: opt -memcpyopt -instcombine -S %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -memcpyopt -instcombine -S %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 %Foo = type { [2048 x i64] }
 
 ; Make sure that all mempcy calls are converted to memset calls, or removed.
diff --git a/llvm/test/Transforms/MemCpyOpt/pr37967.ll b/llvm/test/Transforms/MemCpyOpt/pr37967.ll
--- a/llvm/test/Transforms/MemCpyOpt/pr37967.ll
+++ b/llvm/test/Transforms/MemCpyOpt/pr37967.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -debugify -memcpyopt -check-debugify -S < %s 2>&1 | FileCheck %s
+; RUN: opt -debugify -memcpyopt -check-debugify -S < %s 2>&1 -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -debugify -memcpyopt -check-debugify -S < %s 2>&1 -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 ; CHECK: CheckModuleDebugify: PASS
 
diff --git a/llvm/test/Transforms/MemCpyOpt/process_store.ll b/llvm/test/Transforms/MemCpyOpt/process_store.ll
--- a/llvm/test/Transforms/MemCpyOpt/process_store.ll
+++ b/llvm/test/Transforms/MemCpyOpt/process_store.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -S -memcpyopt | FileCheck %s
+; RUN: opt < %s -S -memcpyopt -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -S -memcpyopt -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/MemCpyOpt/profitable-memset.ll b/llvm/test/Transforms/MemCpyOpt/profitable-memset.ll
--- a/llvm/test/Transforms/MemCpyOpt/profitable-memset.ll
+++ b/llvm/test/Transforms/MemCpyOpt/profitable-memset.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
 
diff --git a/llvm/test/Transforms/MemCpyOpt/smaller.ll b/llvm/test/Transforms/MemCpyOpt/smaller.ll
--- a/llvm/test/Transforms/MemCpyOpt/smaller.ll
+++ b/llvm/test/Transforms/MemCpyOpt/smaller.ll
@@ -1,6 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -memcpyopt -S < %s | FileCheck %s
-; RUN: opt -passes=memcpyopt -S < %s | FileCheck %s
+; RUN: opt -memcpyopt -S < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -memcpyopt -S < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
+; RUN: opt -passes=memcpyopt -S < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -passes=memcpyopt -S < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 ; rdar://8875553
 
 ; Memcpyopt shouldn't optimize the second memcpy using the first
diff --git a/llvm/test/Transforms/MemCpyOpt/sret.ll b/llvm/test/Transforms/MemCpyOpt/sret.ll
--- a/llvm/test/Transforms/MemCpyOpt/sret.ll
+++ b/llvm/test/Transforms/MemCpyOpt/sret.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -basic-aa -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
 target triple = "i686-apple-darwin9"
diff --git a/llvm/test/Transforms/MemCpyOpt/stackrestore.ll b/llvm/test/Transforms/MemCpyOpt/stackrestore.ll
--- a/llvm/test/Transforms/MemCpyOpt/stackrestore.ll
+++ b/llvm/test/Transforms/MemCpyOpt/stackrestore.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -memcpyopt < %s | FileCheck %s
+; RUN: opt -S -memcpyopt < %s -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -S -memcpyopt < %s -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 ; PR40118: BasicAA didn't realize that stackrestore ends the lifetime of
 ; unescaped dynamic allocas, such as those that might come from inalloca.
diff --git a/llvm/test/Transforms/MemCpyOpt/store-to-memset-is-nonzero-type.ll b/llvm/test/Transforms/MemCpyOpt/store-to-memset-is-nonzero-type.ll
--- a/llvm/test/Transforms/MemCpyOpt/store-to-memset-is-nonzero-type.ll
+++ b/llvm/test/Transforms/MemCpyOpt/store-to-memset-is-nonzero-type.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S < %s -memcpyopt | FileCheck %s
+; RUN: opt -S < %s -memcpyopt -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt -S < %s -memcpyopt -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 ; Array
 
diff --git a/llvm/test/Transforms/MemCpyOpt/store-to-memset.ll b/llvm/test/Transforms/MemCpyOpt/store-to-memset.ll
--- a/llvm/test/Transforms/MemCpyOpt/store-to-memset.ll
+++ b/llvm/test/Transforms/MemCpyOpt/store-to-memset.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -memcpyopt -S | FileCheck %s
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-grtev4-linux-gnu"
 
diff --git a/llvm/test/Transforms/MemCpyOpt/vscale-memset.ll b/llvm/test/Transforms/MemCpyOpt/vscale-memset.ll
--- a/llvm/test/Transforms/MemCpyOpt/vscale-memset.ll
+++ b/llvm/test/Transforms/MemCpyOpt/vscale-memset.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -memcpyopt -dce -S | FileCheck %s
+; RUN: opt < %s -memcpyopt -dce -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO_MSSA
+; RUN: opt < %s -memcpyopt -dce -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
 
 ; Negative test
 ; Check this test is not transformed into memset, or cause a compiler warning