Index: conf/default.conf.php
===================================================================
--- conf/default.conf.php
+++ conf/default.conf.php
@@ -1018,10 +1018,6 @@
   // "phd debug" are always launched in trace mdoe. See also 'phd.verbose'.
   'phd.trace' => false,
 
-  // Path to custom celerity resource map relative to 'phabricator/src'.
-  // See also `scripts/celerity_mapper.php`.
-  'celerity.resource-path' => '__celerity_resource_map__.php',
-
   // This value is an input to the hash function when building resource hashes.
   // It has no security value, but if you accidentally poison user caches (by
   // pushing a bad patch or having something go wrong with a CDN, e.g.) you can
Index: scripts/celerity_mapper.php
===================================================================
--- scripts/celerity_mapper.php
+++ scripts/celerity_mapper.php
@@ -190,17 +190,6 @@
 $args->parse(
   array(
     array(
-      'name'     => 'output',
-      'param'    => 'path',
-      'default'  => '../src/__celerity_resource_map__.php',
-      'help'     => "Set the path for resource map. It is usually useful for ".
-                    "'celerity.resource-path' configuration.",
-    ),
-    array(
-      'name'     => 'with-custom',
-      'help'     => 'Include resources in <webroot>/rsrc/custom/.',
-    ),
-    array(
       'name'     => 'webroot',
       'wildcard' => true,
     ),
@@ -212,8 +201,9 @@
 }
 $root = Filesystem::resolvePath(reset($root));
 
-$celerity_path = Filesystem::resolvePath($args->getArg('output'), $root);
-$with_custom = $args->getArg('with-custom');
+$celerity_path = Filesystem::resolvePath(
+  '../src/__celerity_resource_map__.php',
+  $root);
 
 $resource_hash = PhabricatorEnv::getEnvConfig('celerity.resource-hash');
 $runtime_map = array();
@@ -227,9 +217,6 @@
   ->withSuffix('swf')
   ->withFollowSymlinks(true)
   ->setGenerateChecksums(true);
-if (!$with_custom) {
-  $finder->excludePath('./rsrc/custom');
-}
 $raw_files = $finder->find();
 
 echo "Processing ".count($raw_files)." files";
@@ -261,9 +248,6 @@
   ->withSuffix('css')
   ->withFollowSymlinks(true)
   ->setGenerateChecksums(true);
-if (!$with_custom) {
-  $finder->excludePath('./rsrc/custom');
-}
 $files = $finder->find();
 
 echo "Processing ".count($files)." files";
Index: src/applications/config/check/PhabricatorSetupCheckExtraConfig.php
===================================================================
--- src/applications/config/check/PhabricatorSetupCheckExtraConfig.php
+++ src/applications/config/check/PhabricatorSetupCheckExtraConfig.php
@@ -167,6 +167,9 @@
       'differential.anonymous-access' => pht(
         'Phabricator now has meaningful global access controls. See '.
         '`policy.allow-public`.'),
+      'celerity.resource-path' => pht(
+        'An alternate resource map is no longer supported. Instead, use '.
+        'multiple maps. See T4222.'),
     );
 
     return $ancient_config;
Index: src/applications/config/option/PhabricatorExtendingPhabricatorConfigOptions.php
===================================================================
--- src/applications/config/option/PhabricatorExtendingPhabricatorConfigOptions.php
+++ src/applications/config/option/PhabricatorExtendingPhabricatorConfigOptions.php
@@ -28,18 +28,6 @@
             "occur. Specify a list of classes which extend ".
             "PhabricatorEventListener here."))
         ->addExample('MyEventListener', pht('Valid Setting')),
-      $this->newOption(
-        'celerity.resource-path',
-        'string',
-        '__celerity_resource_map__.php')
-        ->setLocked(true)
-        ->setSummary(
-          pht("Custom celerity resource map."))
-        ->setDescription(
-          pht(
-            "Path to custom celerity resource map relative to ".
-            "'phabricator/src'. See also `scripts/celerity_mapper.php`."))
-        ->addExample('local/my_celerity_map.php', pht('Valid Setting')),
        $this->newOption(
          'aphront.default-application-configuration-class',
          'class',
Index: src/infrastructure/celerity/CelerityResourceMap.php
===================================================================
--- src/infrastructure/celerity/CelerityResourceMap.php
+++ src/infrastructure/celerity/CelerityResourceMap.php
@@ -20,12 +20,11 @@
       self::$instance = new CelerityResourceMap();
       $root = phutil_get_library_root('phabricator');
 
-      $path = PhabricatorEnv::getEnvConfig('celerity.resource-path');
+      $path = '__celerity_resource_map__.php';
       $ok = include_once $root.'/'.$path;
       if (!$ok) {
         throw new Exception(
-          "Failed to load Celerity resource map! Check the ".
-          "'celerity.resource-path' setting in your configuration.");
+          "Failed to load Celerity resource map!");
       }
     }
     return self::$instance;