Index: lib/Transform/ZoneAlgo.cpp
===================================================================
--- lib/Transform/ZoneAlgo.cpp
+++ lib/Transform/ZoneAlgo.cpp
@@ -338,11 +338,34 @@
     if (!isl_union_map_is_disjoint(Stores.keep(), AccRel.keep())) {
       OptimizationRemarkMissed R(PassName, "StoreAfterStore",
                                  MA->getAccessInstruction());
-      R << "store after store of same element in same statement";
-      R << " (previous stores: " << Stores;
-      R << ", storing: " << AccRel << ")";
-      S->getFunction().getContext().diagnose(R);
-      return false;
+
+      // Stores to the same location are OK, if the very same value is
+      // stored. Check for this exception.
+      Value *V = nullptr;
+      bool IsOK = true;
+      for (auto *MA : *Stmt) {
+        if (!MA->isLatestArrayKind() || !MA->isMustWrite() ||
+            !MA->isOriginalArrayKind())
+          continue;
+
+        if (!V) {
+          V = MA->getAccessValue();
+        } else {
+          if (V == MA->getAccessValue()) {
+            continue;
+          } else {
+            IsOK = false;
+            break;
+          }
+        }
+      }
+      if (!IsOK) {
+        R << "store after store of same element in same statement";
+        R << " (previous stores: " << Stores;
+        R << ", storing: " << AccRel << ")";
+        S->getFunction().getContext().diagnose(R);
+        return false;
+      }
     }
 
     Stores = give(isl_union_map_union(Stores.take(), AccRel.take()));
Index: test/ForwardOpTree/forward_load_double_write.ll
===================================================================
--- /dev/null
+++ test/ForwardOpTree/forward_load_double_write.ll
@@ -0,0 +1,55 @@
+; RUN: opt %loadPolly -polly-optree -analyze < %s | FileCheck %s -match-full-lines
+;
+; Rematerialize a load.
+;
+define void @func(i32 %n, double* noalias nonnull %A, double* noalias nonnull %B) {
+entry:
+  br label %for
+
+for:
+  %j = phi i32 [0, %entry], [%j.inc, %inc]
+  %j.cmp = icmp slt i32 %j, %n
+  br i1 %j.cmp, label %bodyA, label %exit
+
+    bodyA:
+      %B_idx = getelementptr inbounds double, double* %B, i32 %j
+      %val = load double, double* %B_idx
+      br label %bodyB
+
+    bodyB:
+      %A_idx = getelementptr inbounds double, double* %A, i32 %j
+      store double %val, double* %A_idx
+      store double %val, double* %A_idx
+      br label %inc
+
+inc:
+  %j.inc = add nuw nsw i32 %j, 1
+  br label %for
+
+exit:
+  br label %return
+
+return:
+  ret void
+}
+
+
+; CHECK: Statistics {
+; CHECK:     Known loads forwarded: 1
+; CHECK:     Operand trees forwarded: 1
+; CHECK:     Statements with forwarded operand trees: 1
+; CHECK: }
+
+; CHECK:      Stmt_bodyB
+; CHECK-NEXT:         ReadAccess :=       [Reduction Type: NONE] [Scalar: 0]
+; CHECK-NEXT:             null;
+; CHECK-NEXT:        new: [n] -> { Stmt_bodyB[i0] -> MemRef_B[i0] };
+; CHECK-NEXT:         MustWriteAccess :=  [Reduction Type: NONE] [Scalar: 0]
+; CHECK-NEXT:             [n] -> { Stmt_bodyB[i0] -> MemRef_A[i0] };
+; CHECK-NEXT:         MustWriteAccess :=  [Reduction Type: NONE] [Scalar: 0]
+; CHECK-NEXT:             [n] -> { Stmt_bodyB[i0] -> MemRef_A[i0] };
+; CHECK-NEXT:         Instructions {
+; CHECK-NEXT:               %val = load double, double* %B_idx
+; CHECK-NEXT:               store double %val, double* %A_idx
+; CHECK-NEXT:               store double %val, double* %A_idx
+; CHECK-NEXT:         }