diff --git a/src/dawn/native/CommandEncoder.cpp b/src/dawn/native/CommandEncoder.cpp
index adcbedc..0c2b901 100644
--- a/src/dawn/native/CommandEncoder.cpp
+++ b/src/dawn/native/CommandEncoder.cpp
@@ -1478,7 +1478,8 @@
                                  destination);
                 DAWN_TRY(ValidateB2BCopyAlignment(size, sourceOffset, destinationOffset));
 
-                DAWN_TRY_CONTEXT(ValidateCanUseAs(source, wgpu::BufferUsage::CopySrc),
+                DAWN_TRY_CONTEXT(ValidateCanUseAsInternal(
+                                     source, wgpu::BufferUsage::CopySrc | kInternalCopySrcBuffer),
                                  "validating source %s usage.", source);
                 DAWN_TRY_CONTEXT(ValidateCanUseAs(destination, wgpu::BufferUsage::CopyDst),
                                  "validating destination %s usage.", destination);
diff --git a/src/dawn/native/CommandValidation.cpp b/src/dawn/native/CommandValidation.cpp
index 8ed9dab..1b9989f 100644
--- a/src/dawn/native/CommandValidation.cpp
+++ b/src/dawn/native/CommandValidation.cpp
@@ -655,6 +655,12 @@
     return {};
 }
 
+MaybeError ValidateCanUseAsInternal(const BufferBase* buffer, wgpu::BufferUsage usage) {
+    DAWN_INVALID_IF(!(buffer->GetUsage() & usage), "%s internal usage (%s) doesn't include %s.",
+                    buffer, buffer->GetUsage(), usage);
+    return {};
+}
+
 namespace {
 std::string TextureFormatsToString(const ColorAttachmentFormats& formats) {
     std::ostringstream ss;
diff --git a/src/dawn/native/CommandValidation.h b/src/dawn/native/CommandValidation.h
index b07ad87..36e737f 100644
--- a/src/dawn/native/CommandValidation.h
+++ b/src/dawn/native/CommandValidation.h
@@ -114,6 +114,7 @@
                             wgpu::TextureUsage usage,
                             UsageValidationMode mode);
 MaybeError ValidateCanUseAs(const BufferBase* buffer, wgpu::BufferUsage usage);
+MaybeError ValidateCanUseAsInternal(const BufferBase* buffer, wgpu::BufferUsage usage);
 
 using ColorAttachmentFormats = absl::InlinedVector<const Format*, kMaxColorAttachments>;
 MaybeError ValidateColorAttachmentBytesPerSample(DeviceBase* device,
diff --git a/src/dawn/native/d3d11/BufferD3D11.cpp b/src/dawn/native/d3d11/BufferD3D11.cpp
index af37447..1346d40 100644
--- a/src/dawn/native/d3d11/BufferD3D11.cpp
+++ b/src/dawn/native/d3d11/BufferD3D11.cpp
@@ -52,7 +52,8 @@
 
 namespace {
 
-constexpr wgpu::BufferUsage kCopyUsages = wgpu::BufferUsage::CopySrc | wgpu::BufferUsage::CopyDst;
+constexpr wgpu::BufferUsage kCopyUsages =
+    wgpu::BufferUsage::CopySrc | wgpu::BufferUsage::CopyDst | kInternalCopySrcBuffer;
 
 constexpr wgpu::BufferUsage kStagingUsages = kMappableBufferUsages | kCopyUsages;
 
@@ -75,7 +76,9 @@
 }
 
 bool IsUpload(wgpu::BufferUsage usage) {
-    return usage == (wgpu::BufferUsage::CopySrc | wgpu::BufferUsage::MapWrite);
+    return usage & wgpu::BufferUsage::MapWrite &&
+           IsSubset(usage, kInternalCopySrcBuffer | wgpu::BufferUsage::CopySrc |
+                               wgpu::BufferUsage::MapWrite);
 }
 
 bool IsStaging(wgpu::BufferUsage usage) {
@@ -829,7 +832,8 @@
     // We need to create a separate storage for uniform usage, because D3D11 doesn't allow constant
     // buffer to be used for other purposes.
     if (usagesToHandle & wgpu::BufferUsage::Uniform) {
-        usagesToHandle &= ~(wgpu::BufferUsage::Uniform | wgpu::BufferUsage::CopySrc);
+        usagesToHandle &=
+            ~(wgpu::BufferUsage::Uniform | wgpu::BufferUsage::CopySrc | kInternalCopySrcBuffer);
 
         // Since D3D11 doesn't allow both CPU & GPU to write to a buffer, we need separate
         // storages for CPU writes and GPU writes.
diff --git a/src/dawn/native/dawn_platform.h b/src/dawn/native/dawn_platform.h
index 1fe5e37..f30940f 100644
--- a/src/dawn/native/dawn_platform.h
+++ b/src/dawn/native/dawn_platform.h
@@ -51,8 +51,15 @@
 static constexpr wgpu::BufferUsage kReadOnlyStorageBuffer =
     static_cast<wgpu::BufferUsage>(1u << 30);
 
+// Add an extra buffer usage (copy-src buffer usage) that can be combined with MapRead
+static constexpr wgpu::BufferUsage kInternalCopySrcBuffer =
+    static_cast<wgpu::BufferUsage>(1u << 29);
+
+// TODO(350497225): We should store Buffer's internal and external usage in separate member
+// variables, so that the external usage can be queried directly without bit hacks using this
+// special flag.
 static constexpr wgpu::BufferUsage kAllInternalBufferUsages =
-    kInternalStorageBuffer | kReadOnlyStorageBuffer;
+    kInternalStorageBuffer | kReadOnlyStorageBuffer | kInternalCopySrcBuffer;
 
 // Extra texture usages
 // Usage to denote an extra tag value used in system specific ways.
diff --git a/src/dawn/native/vulkan/BufferVk.cpp b/src/dawn/native/vulkan/BufferVk.cpp
index 57a3f12..46bd395 100644
--- a/src/dawn/native/vulkan/BufferVk.cpp
+++ b/src/dawn/native/vulkan/BufferVk.cpp
@@ -55,7 +55,7 @@
 VkBufferUsageFlags VulkanBufferUsage(wgpu::BufferUsage usage) {
     VkBufferUsageFlags flags = 0;
 
-    if (usage & wgpu::BufferUsage::CopySrc) {
+    if (usage & (wgpu::BufferUsage::CopySrc | kInternalCopySrcBuffer)) {
         flags |= VK_BUFFER_USAGE_TRANSFER_SRC_BIT;
     }
     if (usage & wgpu::BufferUsage::CopyDst) {
@@ -89,7 +89,8 @@
     if (usage & kMappableBufferUsages) {
         flags |= VK_PIPELINE_STAGE_HOST_BIT;
     }
-    if (usage & (wgpu::BufferUsage::CopySrc | wgpu::BufferUsage::CopyDst)) {
+    if (usage &
+        (wgpu::BufferUsage::CopySrc | wgpu::BufferUsage::CopyDst | kInternalCopySrcBuffer)) {
         flags |= VK_PIPELINE_STAGE_TRANSFER_BIT;
     }
     if (usage & (wgpu::BufferUsage::Index | wgpu::BufferUsage::Vertex)) {
@@ -125,7 +126,7 @@
     if (usage & wgpu::BufferUsage::MapWrite) {
         flags |= VK_ACCESS_HOST_WRITE_BIT;
     }
-    if (usage & wgpu::BufferUsage::CopySrc) {
+    if (usage & (wgpu::BufferUsage::CopySrc | kInternalCopySrcBuffer)) {
         flags |= VK_ACCESS_TRANSFER_READ_BIT;
     }
     if (usage & wgpu::BufferUsage::CopyDst) {