vercel-labs · vercel-gh-bot-2 · Jul 21, 2026 · Jul 21, 2026
diff --git a/packages/next/src/build/webpack/loaders/next-swc-loader.ts b/packages/next/src/build/webpack/loaders/next-swc-loader.ts
@@ -102,6 +102,14 @@ async function loaderTransform(
   }
 
   let loaderOptions: SWCLoaderOptions = this.getOptions() || {}
+  const moduleLayer = this._module?.layer
+  if (loaderOptions.bundleLayer == null && moduleLayer != null) {
+    loaderOptions = {
+      ...loaderOptions,
+      bundleLayer: moduleLayer as WebpackLayerName,
+    }
+  }
+
   const shouldMaybeExclude = maybeExclude(
     filename,
     loaderOptions.transpilePackages || []

diff --git a/test/e2e/app-dir/mdx-metadata/app/layout.tsx b/test/e2e/app-dir/mdx-metadata/app/layout.tsx
@@ -0,0 +1,8 @@
+import { ReactNode } from 'react'
+export default function Root({ children }: { children: ReactNode }) {
+  return (
+    <html>
+      <body>{children}</body>
+    </html>
+  )
+}
diff --git a/test/e2e/app-dir/mdx-metadata/app/page.mdx b/test/e2e/app-dir/mdx-metadata/app/page.mdx
@@ -0,0 +1,5 @@
+export const metadata = {
+  title: 'MDX metadata title',
+}
+
+# MDX metadata page
diff --git a/test/e2e/app-dir/mdx-metadata/mdx-components.tsx b/test/e2e/app-dir/mdx-metadata/mdx-components.tsx
@@ -0,0 +1,3 @@
+export function useMDXComponents() {
+  return {}
+}
diff --git a/test/e2e/app-dir/mdx-metadata/mdx-metadata.test.ts b/test/e2e/app-dir/mdx-metadata/mdx-metadata.test.ts
@@ -0,0 +1,30 @@
+import { nextTestSetup } from 'e2e-utils'
+
+describe('mdx metadata export', () => {
+  const { next, isNextStart, skipped } = nextTestSetup({
+    files: __dirname,
+    dependencies: {
+      '@next/mdx': 'canary',
+      '@mdx-js/loader': '^3.1.1',
+      '@mdx-js/react': '^3.1.1',
+    },
+    skipDeployment: true,
+    skipStart: true,
+  })
+
+  if (skipped) return
+
+  if (!isNextStart) {
+    it('skipped in development mode', () => {})
+    return
+  }
+
+  it('builds an MDX page that exports metadata', async () => {
+    const { exitCode } = await next.build()
+    expect(exitCode).toBe(0)
+
+    const html = await next.readFile('.next/server/app/index.html')
+    expect(html).toContain('<title>MDX metadata title</title>')
+    expect(html).toContain('<h1>MDX metadata page</h1>')
+  })
+})
diff --git a/test/e2e/app-dir/mdx-metadata/next.config.js b/test/e2e/app-dir/mdx-metadata/next.config.js
@@ -0,0 +1,8 @@
+const withMDX = require('@next/mdx')()
+
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  pageExtensions: ['js', 'jsx', 'ts', 'tsx', 'md', 'mdx'],
+}
+
+module.exports = withMDX(nextConfig)