diff --git a/llvm/lib/Analysis/MemorySSAUpdater.cpp b/llvm/lib/Analysis/MemorySSAUpdater.cpp
--- a/llvm/lib/Analysis/MemorySSAUpdater.cpp
+++ b/llvm/lib/Analysis/MemorySSAUpdater.cpp
@@ -436,10 +436,10 @@
     MemoryAccess *FirstDef = &*MSSA->getWritableBlockDefs(StartBlock)->begin();
     // Convert to incoming value if it's a memorydef. A phi *is* already an
     // incoming value.
-    if (auto *MD = dyn_cast<MemoryDef>(FirstDef))
-      FirstDef = MD->getDefiningAccess();
+    if (auto *MDL = dyn_cast<MemoryDef>(FirstDef))
+      FirstDef = MDL->getDefiningAccess();
 
-    MSSA->renamePass(MD->getBlock(), FirstDef, Visited);
+    MSSA->renamePass(FirstDef->getBlock(), FirstDef, Visited);
     // We just inserted a phi into this block, so the incoming value will become
     // the phi anyway, so it does not matter what we pass.
     for (auto &MP : InsertedPHIs) {
diff --git a/llvm/test/Analysis/MemorySSA/pr45927.ll b/llvm/test/Analysis/MemorySSA/pr45927.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Analysis/MemorySSA/pr45927.ll
@@ -0,0 +1,73 @@
+; RUN: opt -disable-output -loop-simplify -lcssa -licm -print-memoryssa < %s 2>&1 | FileCheck %s
+; RUN: opt -disable-output -aa-pipeline=basic-aa -passes='loop-mssa(licm),print<memoryssa>' < %s 2>&1 | FileCheck %s
+
+
+@a = external dso_local global i16, align 1
+@c = external dso_local global i16, align 1
+
+; CHECK-LABEL: @main()
+
+; CHECK: entry:
+; CHECK-NEXT: %res.addr.i = alloca i16
+; CHECK-NEXT: ; MemoryUse(liveOnEntry)
+; CHECK-NEXT: %c.promoted = load i16, i16* @c
+; CHECK-NEXT: br label %for.cond.i
+
+; CHECK: for.cond.i:
+; CHECK-NEXT: ; [[NO5:.*]] = MemoryPhi({entry,liveOnEntry},{f.exit.i,[[NO5]]})
+; CHECK-NEXT: %inc.i1 = phi i16 [ %inc.i, %f.exit.i ], [ %c.promoted, %entry ]
+; CHECK-NEXT: %inc.i = add nsw i16 %inc.i1, 1
+; CHECK-NEXT: br i1 false, label %f.exit.thread.i, label %f.exit.i
+
+; CHECK: f.exit.thread.i:
+; CHECK-NEXT: %inc.i.lcssa = phi i16 [ %inc.i, %for.cond.i ]
+; CHECK-NEXT: ; [[NO6:.*]] = MemoryDef([[NO5]])
+; CHECK-NEXT: store i16 %inc.i.lcssa, i16* @c, align 1
+; CHECK-NEXT: ; [[NO2:.*]] = MemoryDef([[NO6]])
+; CHECK-NEXT: store i16 1, i16* @a, align 1
+; CHECK-NEXT: ; MemoryUse([[NO2]])
+; CHECK-NEXT: %tmp2 = load i16, i16* @c, align 1
+; CHECK-NEXT: br label %g.exit
+
+; CHECK: f.exit.i
+; CHECK-NEXT: br i1 false, label %g.exit.loopexit, label %for.cond.i
+
+; CHECK: g.exit.loopexit:
+; CHECK-NEXT: %inc.i.lcssa2 = phi i16 [ %inc.i, %f.exit.i ]
+; CHECK-NEXT: ; [[NO7:.*]] = MemoryDef([[NO5]])
+; CHECK-NEXT: store i16 %inc.i.lcssa2, i16* @c, align 1
+; CHECK-NEXT: br label %g.exit
+
+; CHECK: g.exit
+; CHECK-NEXT: ; [[NO4:.*]] = MemoryPhi({f.exit.thread.i,[[NO2]]},{g.exit.loopexit,[[NO7]]})
+; CHECK-NEXT: ; MemoryUse([[NO4]])
+; CHECK-NEXT:  %tmp1 = load i16, i16* @c, align 1
+; CHECK-NEXT: ; [[NO3:.*]] = MemoryDef([[NO4]])
+; CHECK-NEXT:  store i16 %tmp1, i16* %res.addr.i, align 1
+; CHECK-NEXT:  ret void
+
+define dso_local void @main() {
+entry:
+  %res.addr.i = alloca i16, align 1
+  br label %for.cond.i
+
+for.cond.i:                                       ; preds = %f.exit.i, %entry
+  %tmp0 = load i16, i16* @c, align 1
+  %inc.i = add nsw i16 %tmp0, 1
+  store i16 %inc.i, i16* @c, align 1
+  br i1 false, label %f.exit.thread.i, label %f.exit.i
+
+f.exit.thread.i:                                  ; preds = %for.cond.i
+  store i16 1, i16* @a, align 1
+  %tmp2 = load i16, i16* @c, align 1
+  br label %g.exit
+
+f.exit.i:                                         ; preds = %for.cond.i
+  br i1 false, label %g.exit, label %for.cond.i
+
+g.exit:                                           ; preds = %f.exit.i, %f.exit.thread.i
+  %tmp1 = load i16, i16* @c, align 1
+  store i16 %tmp1, i16* %res.addr.i, align 1
+  ret void
+}
+