diff --git a/src/dawn_native/Queue.cpp b/src/dawn_native/Queue.cpp
index efc716701b..372885bd92 100644
--- a/src/dawn_native/Queue.cpp
+++ b/src/dawn_native/Queue.cpp
@@ -281,4 +281,38 @@ namespace dawn_native {
         return {};
     }
 
+    void CopyTextureData(uint8_t* dstPointer,
+                         const uint8_t* srcPointer,
+                         uint32_t depth,
+                         uint32_t rowsPerImageInBlock,
+                         uint64_t imageAdditionalStride,
+                         uint32_t actualBytesPerRow,
+                         uint32_t dstBytesPerRow,
+                         uint32_t srcBytesPerRow) {
+        bool copyWholeLayer =
+            actualBytesPerRow == dstBytesPerRow && dstBytesPerRow == srcBytesPerRow;
+        bool copyWholeData = copyWholeLayer && imageAdditionalStride == 0;
+
+        if (!copyWholeLayer) {  // copy row by row
+            for (uint32_t d = 0; d < depth; ++d) {
+                for (uint32_t h = 0; h < rowsPerImageInBlock; ++h) {
+                    memcpy(dstPointer, srcPointer, actualBytesPerRow);
+                    dstPointer += dstBytesPerRow;
+                    srcPointer += srcBytesPerRow;
+                }
+                srcPointer += imageAdditionalStride;
+            }
+        } else {
+            uint64_t layerSize = rowsPerImageInBlock * actualBytesPerRow;
+            if (!copyWholeData) {  // copy layer by layer
+                for (uint32_t d = 0; d < depth; ++d) {
+                    memcpy(dstPointer, srcPointer, layerSize);
+                    dstPointer += layerSize;
+                    srcPointer += layerSize + imageAdditionalStride;
+                }
+            } else {  // do a single copy
+                memcpy(dstPointer, srcPointer, layerSize * depth);
+            }
+        }
+    }
 }  // namespace dawn_native
diff --git a/src/dawn_native/Queue.h b/src/dawn_native/Queue.h
index 694d53b845..aad5175334 100644
--- a/src/dawn_native/Queue.h
+++ b/src/dawn_native/Queue.h
@@ -76,6 +76,16 @@ namespace dawn_native {
                                         const Extent3D* writeSize) const;
     };
 
+    // A helper function used in Queue::WriteTexture. The destination data layout must not
+    // contain any additional rows per image.
+    void CopyTextureData(uint8_t* dstPointer,
+                         const uint8_t* srcPointer,
+                         uint32_t depth,
+                         uint32_t rowsPerImageInBlock,
+                         uint64_t imageAdditionalStride,
+                         uint32_t actualBytesPerRow,
+                         uint32_t dstBytesPerRow,
+                         uint32_t srcBytesPerRow);
 }  // namespace dawn_native
 
 #endif  // DAWNNATIVE_QUEUE_H_
diff --git a/src/dawn_native/metal/DeviceMTL.mm b/src/dawn_native/metal/DeviceMTL.mm
index d5dbbc5ea5..13cb7dfd08 100644
--- a/src/dawn_native/metal/DeviceMTL.mm
+++ b/src/dawn_native/metal/DeviceMTL.mm
@@ -282,7 +282,6 @@ namespace dawn_native { namespace metal {
         ASSERT(dataLayout.rowsPerImage == (copySize.height));
         ASSERT(dataLayout.bytesPerRow == (copySize.width) / blockWidth * blockSize);
 
-        // TODO(tommek@google.com): Add tests for this in TextureZeroInitTests.
         EnsureDestinationTextureInitialized(texture, *dst, copySize);
 
         // Metal validation layer requires that if the texture's pixel format is a compressed
diff --git a/src/dawn_native/metal/QueueMTL.mm b/src/dawn_native/metal/QueueMTL.mm
index c0245b1b63..016e0cd69a 100644
--- a/src/dawn_native/metal/QueueMTL.mm
+++ b/src/dawn_native/metal/QueueMTL.mm
@@ -43,8 +43,6 @@ namespace dawn_native { namespace metal {
                                               newDataSize, device->GetPendingCommandSerial()));
             ASSERT(uploadHandle.mappedBuffer != nullptr);
 
-            // TODO(tommek@google.com): Add an optimization to do a single memcpy if the data
-            // is already correctly packed.
             uint8_t* dstPointer = static_cast<uint8_t*>(uploadHandle.mappedBuffer);
             const uint8_t* srcPointer = static_cast<const uint8_t*>(data);
             srcPointer += dataLayout->offset;
@@ -58,14 +56,10 @@ namespace dawn_native { namespace metal {
             ASSERT(dataRowsPerImageInBlock >= alignedRowsPerImageInBlock);
             uint64_t imageAdditionalStride =
                 dataLayout->bytesPerRow * (dataRowsPerImageInBlock - alignedRowsPerImageInBlock);
-            for (uint32_t d = 0; d < writeSize->depth; ++d) {
-                for (uint32_t h = 0; h < alignedRowsPerImageInBlock; ++h) {
-                    memcpy(dstPointer, srcPointer, alignedBytesPerRow);
-                    dstPointer += alignedBytesPerRow;
-                    srcPointer += dataLayout->bytesPerRow;
-                }
-                srcPointer += imageAdditionalStride;
-            }
+
+            CopyTextureData(dstPointer, srcPointer, writeSize->depth, alignedRowsPerImageInBlock,
+                            imageAdditionalStride, alignedBytesPerRow, alignedBytesPerRow,
+                            dataLayout->bytesPerRow);
 
             return uploadHandle;
         }
diff --git a/src/dawn_native/vulkan/QueueVk.cpp b/src/dawn_native/vulkan/QueueVk.cpp
index 99a05909a8..b19b2368c4 100644
--- a/src/dawn_native/vulkan/QueueVk.cpp
+++ b/src/dawn_native/vulkan/QueueVk.cpp
@@ -52,8 +52,6 @@ namespace dawn_native { namespace vulkan {
                                               device->GetPendingCommandSerial()));
             ASSERT(uploadHandle.mappedBuffer != nullptr);
 
-            // TODO(tommek@google.com): Add an optimization to do a single memcpy if the data
-            // is already correctly packed.
             uint8_t* dstPointer = static_cast<uint8_t*>(uploadHandle.mappedBuffer);
             const uint8_t* srcPointer = static_cast<const uint8_t*>(data);
             srcPointer += dataLayout->offset;
@@ -72,14 +70,10 @@ namespace dawn_native { namespace vulkan {
             ASSERT(dataRowsPerImageInBlock >= alignedRowsPerImageInBlock);
             uint64_t imageAdditionalStride =
                 dataLayout->bytesPerRow * (dataRowsPerImageInBlock - alignedRowsPerImageInBlock);
-            for (uint32_t d = 0; d < writeSize->depth; ++d) {
-                for (uint32_t h = 0; h < alignedRowsPerImageInBlock; ++h) {
-                    memcpy(dstPointer, srcPointer, alignedBytesPerRow);
-                    dstPointer += optimallyAlignedBytesPerRow;
-                    srcPointer += dataLayout->bytesPerRow;
-                }
-                srcPointer += imageAdditionalStride;
-            }
+
+            CopyTextureData(dstPointer, srcPointer, writeSize->depth, alignedRowsPerImageInBlock,
+                            imageAdditionalStride, alignedBytesPerRow, optimallyAlignedBytesPerRow,
+                            dataLayout->bytesPerRow);
 
             return uploadHandle;
         }