diff --git a/src/__celerity_resource_map__.php b/src/__celerity_resource_map__.php
index 1500a5ed97..7c73c57ed0 100644
--- a/src/__celerity_resource_map__.php
+++ b/src/__celerity_resource_map__.php
@@ -34,6 +34,15 @@ celerity_register_resource_map(array(
     ),
     'disk' => '/rsrc/css/aphront/panel-view.css',
   ),
+  'aphront-request-failure-view-css' =>
+  array(
+    'uri' => '/res/d7df3b42/rsrc/css/aphront/request-failure-view.css',
+    'type' => 'css',
+    'requires' =>
+    array(
+    ),
+    'disk' => '/rsrc/css/aphront/request-failure-view.css',
+  ),
   'aphront-side-nav-view-css' =>
   array(
     'uri' => '/res/0fc0545c/rsrc/css/aphront/side-nav-view.css',
diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 94cf87f8f7..d7dc179c5a 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -45,6 +45,7 @@ phutil_register_library_map(array(
     'AphrontRedirectException' => 'aphront/exception/redirect',
     'AphrontRedirectResponse' => 'aphront/response/redirect',
     'AphrontRequest' => 'aphront/request',
+    'AphrontRequestFailureView' => 'view/page/failure',
     'AphrontResponse' => 'aphront/response/base',
     'AphrontSideNavView' => 'view/layout/sidenav',
     'AphrontTableView' => 'view/control/table',
@@ -97,6 +98,7 @@ phutil_register_library_map(array(
     'DifferentialUnitStatus' => 'applications/differential/constants/unitstatus',
     'Javelin' => 'infratructure/javelin/api',
     'LiskDAO' => 'storage/lisk/dao',
+    'Phabricator404Controller' => 'applications/base/controller/404',
     'PhabricatorAuthController' => 'applications/auth/controlller/base',
     'PhabricatorConduitAPIController' => 'applications/conduit/controller/api',
     'PhabricatorConduitConnectionLog' => 'applications/conduit/storage/connectionlog',
@@ -209,6 +211,7 @@ phutil_register_library_map(array(
     'AphrontQueryRecoverableException' => 'AphrontQueryException',
     'AphrontRedirectException' => 'AphrontException',
     'AphrontRedirectResponse' => 'AphrontResponse',
+    'AphrontRequestFailureView' => 'AphrontView',
     'AphrontSideNavView' => 'AphrontView',
     'AphrontTableView' => 'AphrontView',
     'AphrontWebpageResponse' => 'AphrontResponse',
@@ -240,6 +243,7 @@ phutil_register_library_map(array(
     'DifferentialRevisionListController' => 'DifferentialController',
     'DifferentialRevisionUpdateHistoryView' => 'AphrontView',
     'DifferentialRevisionViewController' => 'DifferentialController',
+    'Phabricator404Controller' => 'PhabricatorController',
     'PhabricatorAuthController' => 'PhabricatorController',
     'PhabricatorConduitAPIController' => 'PhabricatorConduitController',
     'PhabricatorConduitConnectionLog' => 'PhabricatorConduitDAO',
diff --git a/src/aphront/applicationconfiguration/AphrontApplicationConfiguration.php b/src/aphront/applicationconfiguration/AphrontApplicationConfiguration.php
index 32f9bbef9b..cba9578bb4 100644
--- a/src/aphront/applicationconfiguration/AphrontApplicationConfiguration.php
+++ b/src/aphront/applicationconfiguration/AphrontApplicationConfiguration.php
@@ -28,6 +28,7 @@ abstract class AphrontApplicationConfiguration {
   abstract public function getApplicationName();
   abstract public function getURIMap();
   abstract public function buildRequest();
+  abstract public function build404Controller();
 
   final public function setRequest(AphrontRequest $request) {
     $this->request = $request;
@@ -45,6 +46,10 @@ abstract class AphrontApplicationConfiguration {
     $path = $request->getPath();
     list($controller_class, $uri_data) = $mapper->mapPath($path);
 
+    if (!$controller_class) {
+      return $this->build404Controller();
+    }
+
     PhutilSymbolLoader::loadClass($controller_class);
     $controller = newv($controller_class, array($request));
 
diff --git a/src/aphront/default/configuration/AphrontDefaultApplicationConfiguration.php b/src/aphront/default/configuration/AphrontDefaultApplicationConfiguration.php
index a5553423ee..ee7c71caa6 100644
--- a/src/aphront/default/configuration/AphrontDefaultApplicationConfiguration.php
+++ b/src/aphront/default/configuration/AphrontDefaultApplicationConfiguration.php
@@ -150,10 +150,29 @@ class AphrontDefaultApplicationConfiguration
         $response->setContent($view->render());
         return $response;
       }
+    } else if ($response instanceof Aphront404Response) {
+
+      $failure = new AphrontRequestFailureView();
+      $failure->setHeader('404 Not Found');
+      $failure->appendChild(
+        '<p>The page you requested was not found.</p>');
+
+      $view = new PhabricatorStandardPageView();
+      $view->setTitle('404 Not Found');
+      $view->appendChild($failure);
+
+      $response = new AphrontWebpageResponse();
+      $response->setContent($view->render());
+      $response->setHTTPResponseCode(404);
+      return $response;
     }
 
     return $response;
   }
 
+  public function build404Controller() {
+    return array(new Phabricator404Controller($this->getRequest()), array());
+  }
+
 
 }
diff --git a/src/aphront/default/configuration/__init__.php b/src/aphront/default/configuration/__init__.php
index f841860f69..ea6f86450a 100644
--- a/src/aphront/default/configuration/__init__.php
+++ b/src/aphront/default/configuration/__init__.php
@@ -9,6 +9,8 @@
 phutil_require_module('phabricator', 'aphront/applicationconfiguration');
 phutil_require_module('phabricator', 'aphront/request');
 phutil_require_module('phabricator', 'aphront/response/webpage');
+phutil_require_module('phabricator', 'applications/base/controller/404');
+phutil_require_module('phabricator', 'view/page/failure');
 phutil_require_module('phabricator', 'view/page/standard');
 
 phutil_require_module('phutil', 'markup');
diff --git a/src/aphront/response/base/AphrontResponse.php b/src/aphront/response/base/AphrontResponse.php
index 29a371c08d..786f56b77e 100644
--- a/src/aphront/response/base/AphrontResponse.php
+++ b/src/aphront/response/base/AphrontResponse.php
@@ -23,6 +23,7 @@ abstract class AphrontResponse {
 
   private $request;
   private $cacheable = false;
+  private $responseCode = 200;
 
   public function setRequest($request) {
     $this->request = $request;
@@ -36,12 +37,21 @@ abstract class AphrontResponse {
   public function getHeaders() {
     return array();
   }
-  
+
   public function setCacheDurationInSeconds($duration) {
     $this->cacheable = $duration;
     return $this;
   }
 
+  public function setHTTPResponseCode($code) {
+    $this->responseCode = $code;
+    return $this;
+  }
+
+  public function getHTTPResponseCode() {
+    return $this->responseCode;
+  }
+
   public function getCacheHeaders() {
     if ($this->cacheable) {
       $epoch = time() + $this->cacheable;
diff --git a/src/applications/base/controller/404/Phabricator404Controller.php b/src/applications/base/controller/404/Phabricator404Controller.php
new file mode 100644
index 0000000000..591e7a3c3e
--- /dev/null
+++ b/src/applications/base/controller/404/Phabricator404Controller.php
@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * Copyright 2011 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class Phabricator404Controller extends PhabricatorController {
+
+  public function processRequest() {
+    return new Aphront404Response();
+  }
+
+}
diff --git a/src/applications/base/controller/404/__init__.php b/src/applications/base/controller/404/__init__.php
new file mode 100644
index 0000000000..e3accbe46e
--- /dev/null
+++ b/src/applications/base/controller/404/__init__.php
@@ -0,0 +1,13 @@
+<?php
+/**
+ * This file is automatically generated. Lint this module to rebuild it.
+ * @generated
+ */
+
+
+
+phutil_require_module('phabricator', 'aphront/response/404');
+phutil_require_module('phabricator', 'applications/base/controller/base');
+
+
+phutil_require_source('Phabricator404Controller.php');
diff --git a/src/view/page/failure/AphrontRequestFailureView.php b/src/view/page/failure/AphrontRequestFailureView.php
new file mode 100755
index 0000000000..832838e921
--- /dev/null
+++ b/src/view/page/failure/AphrontRequestFailureView.php
@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * Copyright 2011 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+final class AphrontRequestFailureView extends AphrontView {
+
+  private $header;
+
+  public function setHeader($header) {
+    $this->header = $header;
+    return $this;
+  }
+
+
+  final public function render() {
+    require_celerity_resource('aphront-request-failure-view-css');
+    
+    return
+      '<div class="aphront-request-failure-view">'.
+        '<div class="aphront-request-failure-head">'.
+          '<h1>'.phutil_escape_html($this->header).'</h1>'.
+        '</div>'.
+        '<div class="aphront-request-failure-body">'.
+          $this->renderChildren().
+        '</div>'.
+      '</div>';
+  }
+
+}
diff --git a/src/view/page/failure/__init__.php b/src/view/page/failure/__init__.php
new file mode 100644
index 0000000000..e753355fdb
--- /dev/null
+++ b/src/view/page/failure/__init__.php
@@ -0,0 +1,14 @@
+<?php
+/**
+ * This file is automatically generated. Lint this module to rebuild it.
+ * @generated
+ */
+
+
+
+phutil_require_module('phabricator', 'view/base');
+
+phutil_require_module('phutil', 'markup');
+
+
+phutil_require_source('AphrontRequestFailureView.php');
diff --git a/webroot/index.php b/webroot/index.php
index ca2a0ab82d..006c8538cb 100644
--- a/webroot/index.php
+++ b/webroot/index.php
@@ -55,6 +55,12 @@ $response = $application->willSendResponse($response);
 $response->setRequest($request);
 
 $response_string = $response->buildResponseString();
+
+$code = $response->getHTTPResponseCode();
+if ($code != 200) {
+  header("HTTP/1.0 {$code}");
+}
+
 $headers = $response->getCacheHeaders();
 $headers = array_merge($headers, $response->getHeaders());
 foreach ($headers as $header) {
diff --git a/webroot/rsrc/css/aphront/request-failure-view.css b/webroot/rsrc/css/aphront/request-failure-view.css
new file mode 100644
index 0000000000..de13f0a6a0
--- /dev/null
+++ b/webroot/rsrc/css/aphront/request-failure-view.css
@@ -0,0 +1,27 @@
+/**
+ * @provides aphront-request-failure-view-css
+ */
+
+.aphront-request-failure-view {
+  margin: 2em auto;
+  background: #eff2f7;
+  width: 600px;
+}
+
+.aphront-request-failure-view .aphront-request-failure-head {
+  padding: 1em 2em;
+  border-bottom: 1px solid #afb2b7;
+  background: #dfe2e7;
+}
+
+.aphront-request-failure-view .aphront-request-failure-head h1 {
+  font-size: 24px;
+}
+
+.aphront-request-failure-view .aphront-request-failure-body {
+  padding: 1em 2em;
+}
+
+.aphront-request-failure-view .aphront-request-failure-body p {
+  margin: .5em 0 1.25em;
+}