Index: lib/Transforms/Scalar/MemCpyOptimizer.cpp
===================================================================
--- lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -532,10 +532,19 @@
           // position if nothing alias the store memory after this and the store
           // destination is not in the range.
           P = &*I;
+
+          // Make sure this position dominate store's address.
+          if (auto *Addr = dyn_cast<Instruction>(SI->getPointerOperand())) {
+            DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+            if (DT.dominates(P, Addr)) {
+              P = nullptr;
+              break;
+            }
+          }
+
           for (; I != E; ++I) {
             MemoryLocation StoreLoc = MemoryLocation::get(SI);
-            if (&*I == SI->getOperand(1) ||
-                AA.getModRefInfo(&*I, StoreLoc) != MRI_NoModRef) {
+            if (AA.getModRefInfo(&*I, StoreLoc) != MRI_NoModRef) {
               P = nullptr;
               break;
             }
Index: test/Transforms/MemCpyOpt/fca2memcpy.ll
===================================================================
--- test/Transforms/MemCpyOpt/fca2memcpy.ll
+++ test/Transforms/MemCpyOpt/fca2memcpy.ll
@@ -73,11 +73,10 @@
   ret void
 }
 
-
 ; The GEP is present after the aliasing store, preventing to move the memcpy before
 ; (without further analysis/transformation)
 define void @copyaliaswithproducerinbetween(%S* %src, %S* %dst) {
-; CHECK-LABEL: copyalias
+; CHECK-LABEL: copyaliaswithproducerinbetween
 ; CHECK-NEXT: [[LOAD:%[a-z0-9\.]+]] = load %S, %S* %src
 ; CHECK-NOT: call
   %1 = load %S, %S* %src