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
@@ -483,12 +483,6 @@
   if (UO1 != UO2)
     return OW_Unknown;
 
-  // If the "Later" store is to a recognizable object, get its size.
-  uint64_t ObjectSize = getPointerSize(UO2, DL, TLI, F);
-  if (ObjectSize != MemoryLocation::UnknownSize)
-    if (ObjectSize == LaterSize && ObjectSize >= EarlierSize)
-      return OW_Complete;
-
   // Okay, we have stores to two completely different pointers.  Try to
   // decompose the pointer into a "base + constant_offset" form.  If the base
   // pointers are equal, then we can reason about the two stores.
@@ -497,6 +491,22 @@
   const Value *BP1 = GetPointerBaseWithConstantOffset(P1, EarlierOff, DL);
   const Value *BP2 = GetPointerBaseWithConstantOffset(P2, LaterOff, DL);
 
+  // If the "Later" store is to a recognizable object, get its size.
+  uint64_t ObjectSize = getPointerSize(UO2, DL, TLI, F);
+  if (ObjectSize != MemoryLocation::UnknownSize)
+    if (ObjectSize == LaterSize && ObjectSize >= EarlierSize)
+      // If both writes are in the same basic block, there is no need to check
+      // if the writes are fully inside the underlying object, because the
+      // out-of-bounds access is guaranteed to execute. Note that the case when
+      // the block is exited early due to unwinding is already handled
+      // separately by DSE, by considering the unwinding calls as clobbers. If
+      // the writes are not in the same block, make sure they are inside the
+      // underlying object.
+      if (EarlierI->getParent() == LaterI->getParent() ||
+          (EarlierOff + EarlierSize <= ObjectSize &&
+           LaterOff + LaterSize <= ObjectSize))
+        return OW_Complete;
+
   // If the base pointers still differ, we have two completely different stores.
   if (BP1 != BP2)
     return OW_Unknown;
diff --git a/llvm/test/Transforms/DeadStoreElimination/MSSA/out-of-bounds-stores.ll b/llvm/test/Transforms/DeadStoreElimination/MSSA/out-of-bounds-stores.ll
--- a/llvm/test/Transforms/DeadStoreElimination/MSSA/out-of-bounds-stores.ll
+++ b/llvm/test/Transforms/DeadStoreElimination/MSSA/out-of-bounds-stores.ll
@@ -36,6 +36,8 @@
 ; CHECK-NEXT:    [[D:%.*]] = alloca [1 x i32], align 4
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 ; CHECK:       for.body:
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds [1 x i32], [1 x i32]* [[D]], i64 0, i64 0
+; CHECK-NEXT:    store i32 10, i32* [[ARRAYIDX]], align 4
 ; CHECK-NEXT:    br label [[FOR_INC:%.*]]
 ; CHECK:       for.inc:
 ; CHECK-NEXT:    br i1 [[C:%.*]], label [[FOR_BODY_1:%.*]], label [[FOR_END:%.*]]