diff --git a/cmd/godoc/x.go b/cmd/godoc/x.go
new file mode 100644
index 0000000..ed7c8d8
--- /dev/null
+++ b/cmd/godoc/x.go
@@ -0,0 +1,68 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains the handlers that serve go-import redirects for Go
+// sub-repositories. It specifies the mapping from import paths like
+// "golang.org/x/tools" to the actual repository locations.
+
+package main
+
+import (
+	"html/template"
+	"log"
+	"net/http"
+	"strings"
+)
+
+const xPrefix = "/x/"
+
+var xMap = map[string]string{
+	"benchmarks": "https://code.google.com/p/go.benchmarks",
+	"blog":       "https://code.google.com/p/go.blog",
+	"codereview": "https://code.google.com/p/go.codereview",
+	"crypto":     "https://code.google.com/p/go.crypto",
+	"exp":        "https://code.google.com/p/go.exp",
+	"image":      "https://code.google.com/p/go.image",
+	"mobile":     "https://code.google.com/p/go.mobile",
+	"net":        "https://code.google.com/p/go.net",
+	"sys":        "https://code.google.com/p/go.sys",
+	"talks":      "https://code.google.com/p/go.talks",
+	"text":       "https://code.google.com/p/go.text",
+	"tools":      "https://code.google.com/p/go.tools",
+}
+
+func init() {
+	http.HandleFunc(xPrefix, xHandler)
+}
+
+func xHandler(w http.ResponseWriter, r *http.Request) {
+	head, tail := strings.TrimPrefix(r.URL.Path, xPrefix), ""
+	if i := strings.Index(head, "/"); i != -1 {
+		head, tail = head[:i], head[i:]
+	}
+	repo, ok := xMap[head]
+	if !ok {
+		http.NotFound(w, r)
+		return
+	}
+	data := struct {
+		Prefix, Head, Tail, Repo string
+	}{xPrefix, head, tail, repo}
+	if err := xTemplate.Execute(w, data); err != nil {
+		log.Println("xHandler:", err)
+	}
+}
+
+var xTemplate = template.Must(template.New("x").Parse(`<!DOCTYPE html>
+<html>
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
+<meta name="go-import" content="golang.org{{.Prefix}}{{.Head}} hg {{.Repo}}">
+<meta http-equiv="refresh" content="0; url=https://godoc.org/golang.org{{.Prefix}}{{.Head}}{{.Tail}}">
+</head>
+<body>
+Nothing to see here; <a href="https://godoc.org/golang.org{{.Prefix}}{{.Head}}{{.Tail}}">move along</a>.
+</body>
+</html>
+`))