diff --git a/mlir/lib/Conversion/MemRefToLLVM/MemRefToLLVM.cpp b/mlir/lib/Conversion/MemRefToLLVM/MemRefToLLVM.cpp
--- a/mlir/lib/Conversion/MemRefToLLVM/MemRefToLLVM.cpp
+++ b/mlir/lib/Conversion/MemRefToLLVM/MemRefToLLVM.cpp
@@ -1030,10 +1030,9 @@
     auto sourcePtr = promote(unrankedSource);
     auto targetPtr = promote(unrankedTarget);
 
-    unsigned typeSize =
-        mlir::DataLayout::closest(op).getTypeSize(srcType.getElementType());
-    auto elemSize = rewriter.create<LLVM::ConstantOp>(
-        loc, getIndexType(), rewriter.getIndexAttr(typeSize));
+    // Derive size from llvm.getelementptr which will account for any
+    // potential alignment
+    auto elemSize = getSizeInBytes(loc, srcType.getElementType(), rewriter);
     auto copyFn = LLVM::lookupOrCreateMemRefCopyFn(
         op->getParentOfType<ModuleOp>(), getIndexType(), sourcePtr.getType());
     rewriter.create<LLVM::CallOp>(loc, copyFn,
diff --git a/mlir/test/Conversion/MemRefToLLVM/memref-to-llvm.mlir b/mlir/test/Conversion/MemRefToLLVM/memref-to-llvm.mlir
--- a/mlir/test/Conversion/MemRefToLLVM/memref-to-llvm.mlir
+++ b/mlir/test/Conversion/MemRefToLLVM/memref-to-llvm.mlir
@@ -530,7 +530,8 @@
   // CHECK: llvm.store {{%.*}}, [[ALLOCA2]] : !llvm.struct<(i64, ptr)>, !llvm.ptr
   // CHECK: [[ALLOCA3:%.*]] = llvm.alloca [[RANK2]] x !llvm.struct<(i64, ptr)> : (i64) -> !llvm.ptr
   // CHECK: llvm.store [[INSERT2]], [[ALLOCA3]] : !llvm.struct<(i64, ptr)>, !llvm.ptr
-  // CHECK: [[SIZE:%.*]] = llvm.mlir.constant(1 : index) : i64
+  // CHECK: [[SIZEPTR:%.*]] = llvm.getelementptr {{%.*}}[1] : (!llvm.ptr) -> !llvm.ptr, i1
+  // CHECK: [[SIZE:%.*]] = llvm.ptrtoint [[SIZEPTR]] : !llvm.ptr to i64
   // CHECK: llvm.call @memrefCopy([[SIZE]], [[ALLOCA2]], [[ALLOCA3]]) : (i64, !llvm.ptr, !llvm.ptr) -> ()
   // CHECK: llvm.intr.stackrestore [[STACKSAVE]]
   return
diff --git a/mlir/test/Conversion/MemRefToLLVM/typed-pointers.mlir b/mlir/test/Conversion/MemRefToLLVM/typed-pointers.mlir
--- a/mlir/test/Conversion/MemRefToLLVM/typed-pointers.mlir
+++ b/mlir/test/Conversion/MemRefToLLVM/typed-pointers.mlir
@@ -82,7 +82,8 @@
   // CHECK: llvm.store {{%.*}}, [[ALLOCA2]] : !llvm.ptr<struct<(i64, ptr<i8>)>>
   // CHECK: [[ALLOCA3:%.*]] = llvm.alloca [[RANK2]] x !llvm.struct<(i64, ptr<i8>)> : (i64) -> !llvm.ptr<struct<(i64, ptr<i8>)>>
   // CHECK: llvm.store [[INSERT2]], [[ALLOCA3]] : !llvm.ptr<struct<(i64, ptr<i8>)>>
-  // CHECK: [[SIZE:%.*]] = llvm.mlir.constant(1 : index) : i64
+  // CHECK: [[SIZEPTR:%.*]] = llvm.getelementptr {{%.*}}[1] : (!llvm.ptr<i1>) -> !llvm.ptr<i1>
+  // CHECK: [[SIZE:%.*]] = llvm.ptrtoint [[SIZEPTR]] : !llvm.ptr<i1> to i64
   // CHECK: llvm.call @memrefCopy([[SIZE]], [[ALLOCA2]], [[ALLOCA3]]) : (i64, !llvm.ptr<struct<(i64, ptr<i8>)>>, !llvm.ptr<struct<(i64, ptr<i8>)>>) -> ()
   // CHECK: llvm.intr.stackrestore [[STACKSAVE]]
   return