diff --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -2361,6 +2361,40 @@
     return false;
   }
 
+  /// Eliminates writes to variables where the value that is being written
+  /// is already stored in the variable
+  bool eliminateDeadStoresOfExisitingValues() {
+    bool MadeChange = false;
+    LLVM_DEBUG(dbgs() << "Trying to eliminate MemoryDefs that write the "
+                         "already exisiting value\n");
+    for (int I = MemDefs.size() - 1; I >= 0; I--) {
+      MemoryDef *Def = MemDefs[I];
+      if (SkipStores.find(Def) != SkipStores.end() ||
+          !isRemovable(Def->getMemoryInst()))
+        continue;
+      MemoryAccess *DefAccess = dyn_cast<MemoryAccess>(Def);
+      if (!DefAccess || isa<MemoryPhi>(DefAccess))
+        continue;
+      Instruction *DefInst = cast<MemoryUseOrDef>(DefAccess)->getMemoryInst();
+      if (!DefInst)
+        continue;
+      for (auto UI = DefAccess->use_begin(), IE = DefAccess->use_end();
+           UI != IE;) {
+        MemoryAccess *UseAccess = cast<MemoryAccess>((UI++)->getUser());
+        if (MemoryDef *UseDef = dyn_cast_or_null<MemoryDef>(UseAccess)) {
+          Instruction *UseInst = UseDef->getMemoryInst();
+          if (!UseInst)
+            continue;
+          if (UseInst->isIdenticalTo(DefInst)) {
+            deleteDeadInstruction(UseInst);
+            MadeChange = true;
+          }
+        }
+      }
+    }
+    return MadeChange;
+  }
+
   /// Eliminate writes to objects that are not visible in the caller and are not
   /// accessed before returning from the function.
   bool eliminateDeadWritesAtEndOfFunction() {
@@ -2630,6 +2664,8 @@
     }
   }
 
+  MadeChange |= State.eliminateDeadStoresOfExisitingValues();
+
   if (EnablePartialOverwriteTracking)
     for (auto &KV : State.IOLs)
       MadeChange |= removePartiallyOverlappedStores(State.DL, KV.second, TLI);
diff --git a/llvm/test/Transforms/DeadStoreElimination/MSSA/simple.ll b/llvm/test/Transforms/DeadStoreElimination/MSSA/simple.ll
--- a/llvm/test/Transforms/DeadStoreElimination/MSSA/simple.ll
+++ b/llvm/test/Transforms/DeadStoreElimination/MSSA/simple.ll
@@ -509,7 +509,6 @@
 define void @test36(i8* %P, i8* %Q) {
 ; CHECK-LABEL: @test36(
 ; CHECK-NEXT:    tail call void @llvm.memmove.p0i8.p0i8.i64(i8* [[P:%.*]], i8* [[Q:%.*]], i64 12, i1 false)
-; CHECK-NEXT:    tail call void @llvm.memmove.p0i8.p0i8.i64(i8* [[P]], i8* [[Q]], i64 12, i1 false)
 ; CHECK-NEXT:    ret void
 ;
 
@@ -521,7 +520,6 @@
 define void @test36_atomic(i8* %P, i8* %Q) {
 ; CHECK-LABEL: @test36_atomic(
 ; CHECK-NEXT:    tail call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i64(i8* align 1 [[P:%.*]], i8* align 1 [[Q:%.*]], i64 12, i32 1)
-; CHECK-NEXT:    tail call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i64(i8* align 1 [[P]], i8* align 1 [[Q]], i64 12, i32 1)
 ; CHECK-NEXT:    ret void
 ;
 
diff --git a/llvm/test/Transforms/DeadStoreElimination/MSSA/stores-of-existing-values.ll b/llvm/test/Transforms/DeadStoreElimination/MSSA/stores-of-existing-values.ll
--- a/llvm/test/Transforms/DeadStoreElimination/MSSA/stores-of-existing-values.ll
+++ b/llvm/test/Transforms/DeadStoreElimination/MSSA/stores-of-existing-values.ll
@@ -11,7 +11,6 @@
 ; CHECK-NEXT:    store i8 1, i8* [[R:%.*]], align 1
 ; CHECK-NEXT:    br i1 [[B:%.*]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
 ; CHECK:       if.then:
-; CHECK-NEXT:    store i8 1, i8* [[R]], align 1
 ; CHECK-NEXT:    tail call void @fn_mayread_or_clobber()
 ; CHECK-NEXT:    br label [[IF_END:%.*]]
 ; CHECK:       if.else:
@@ -54,7 +53,6 @@
 ; CHECK-NEXT:    tail call void @fn_readonly()
 ; CHECK-NEXT:    br label [[IF_END]]
 ; CHECK:       if.end:
-; CHECK-NEXT:    store i8 1, i8* [[R]], align 1
 ; CHECK-NEXT:    ret void
 ;
 entry:
@@ -181,7 +179,6 @@
 ; CHECK-NEXT:    [[C1:%.*]] = call i1 @cond()
 ; CHECK-NEXT:    br i1 [[C1]], label [[FOR_BODY:%.*]], label [[END:%.*]]
 ; CHECK:       for.body:
-; CHECK-NEXT:    store i32 1, i32* [[P]], align 4
 ; CHECK-NEXT:    [[LV:%.*]] = load i32, i32* [[P]], align 4
 ; CHECK-NEXT:    br label [[FOR_HEADER]]
 ; CHECK:       end:
@@ -216,7 +213,6 @@
 ; CHECK:       bb2:
 ; CHECK-NEXT:    ret void
 ; CHECK:       bb3:
-; CHECK-NEXT:    store i32 0, i32* [[P]], align 4
 ; CHECK-NEXT:    ret void
 ;
   store i32 0, i32* %P
@@ -268,7 +264,6 @@
 ; CHECK-NEXT:    call void @fn_mayread_or_clobber()
 ; CHECK-NEXT:    ret void
 ; CHECK:       bb3:
-; CHECK-NEXT:    store i32 0, i32* [[P]], align 4
 ; CHECK-NEXT:    ret void
 ;
   store i32 0, i32* %P