diff --git a/.changeset/forwarded-host.md b/.changeset/forwarded-host.md
new file mode 100644
index 00000000..22368211
--- /dev/null
+++ b/.changeset/forwarded-host.md
@@ -0,0 +1,5 @@
+---
+"@monetizationos/proxy": minor
+---
+
+Origin requests carry the viewer's host and protocol as `X-Forwarded-Host` and `X-Forwarded-Proto`, so origins can build URLs on the public domain. `originRequestHeaders` can override either.
diff --git a/src/stages/originRequest.ts b/src/stages/originRequest.ts
index 6f34ae6f..3f0de0a5 100644
--- a/src/stages/originRequest.ts
+++ b/src/stages/originRequest.ts
@@ -3,9 +3,15 @@ import type { PipelineContext } from '../context'
 import getTargetUrl from './getTargetUrl'
 
 export default function performOriginRequest(ctx: PipelineContext, request: Request, originFetcher: Fetcher): Promise<Response> {
-    const targetUrl = getTargetUrl(new URL(request.url), ctx.config.originUrl)
+    const viewerUrl = new URL(request.url)
+    const targetUrl = getTargetUrl(viewerUrl, ctx.config.originUrl)
     const originRequest = new Request(targetUrl, request)
 
+    // The origin is fetched on its own host, so pass it the viewer's. originRequestHeaders can override these.
+    originRequest.headers.delete('Forwarded')
+    originRequest.headers.set('X-Forwarded-Host', viewerUrl.host)
+    originRequest.headers.set('X-Forwarded-Proto', viewerUrl.protocol.slice(0, -1))
+
     for (const [name, value] of Object.entries(ctx.config.originRequestHeaders)) {
         originRequest.headers.set(name, value)
     }
diff --git a/test/stages/originRequest.spec.ts b/test/stages/originRequest.spec.ts
index 6cd5db14..1abc8aaa 100644
--- a/test/stages/originRequest.spec.ts
+++ b/test/stages/originRequest.spec.ts
@@ -60,6 +60,31 @@ describe('performOriginRequest', () => {
         expect(headers.get('x-keep')).toBe('client-value')
     })
 
+    it("sends the viewer's host and protocol as X-Forwarded-Host and X-Forwarded-Proto", async () => {
+        const fetcher = MockFetcher(() => new Response('ok'))
+
+        await performOriginRequest(
+            ctx(),
+            new Request('http://news.example.com:8080/page', {
+                headers: { 'X-Forwarded-Host': 'other.example', 'X-Forwarded-Proto': 'https', Forwarded: 'host=other.example' },
+            }),
+            fetcher,
+        )
+
+        const headers = fetcher.calls[0]!.request.headers
+        expect(headers.get('x-forwarded-host')).toBe('news.example.com:8080')
+        expect(headers.get('x-forwarded-proto')).toBe('http')
+        expect(headers.has('forwarded')).toBe(false)
+    })
+
+    it('lets origin request headers override the forwarded headers', async () => {
+        const fetcher = MockFetcher(() => new Response('ok'))
+
+        await performOriginRequest(ctx({ 'X-Forwarded-Host': 'origin.example.com' }), new Request('https://news.example.com/page'), fetcher)
+
+        expect(fetcher.calls[0]!.request.headers.get('x-forwarded-host')).toBe('origin.example.com')
+    })
+
     it('preserves method and body while adding origin request headers', async () => {
         const fetcher = MockFetcher(async (request) => {
             expect(request.method).toBe('POST')