Index: src/__phutil_library_map__.php
===================================================================
--- src/__phutil_library_map__.php
+++ src/__phutil_library_map__.php
@@ -3676,7 +3676,11 @@
     'PhabricatorPhrequentConfigOptions' => 'PhabricatorApplicationConfigOptions',
     'PhabricatorPhrictionConfigOptions' => 'PhabricatorApplicationConfigOptions',
     'PhabricatorPolicies' => 'PhabricatorPolicyConstants',
-    'PhabricatorPolicy' => 'PhabricatorPolicyDAO',
+    'PhabricatorPolicy' =>
+    array(
+      0 => 'PhabricatorPolicyDAO',
+      1 => 'PhabricatorPolicyInterface',
+    ),
     'PhabricatorPolicyAwareQuery' => 'PhabricatorOffsetPagedQuery',
     'PhabricatorPolicyAwareTestQuery' => 'PhabricatorPolicyAwareQuery',
     'PhabricatorPolicyCapability' => 'Phobject',
@@ -3694,7 +3698,7 @@
     'PhabricatorPolicyManagementUnlockWorkflow' => 'PhabricatorPolicyManagementWorkflow',
     'PhabricatorPolicyManagementWorkflow' => 'PhutilArgumentWorkflow',
     'PhabricatorPolicyPHIDTypePolicy' => 'PhabricatorPHIDType',
-    'PhabricatorPolicyQuery' => 'PhabricatorQuery',
+    'PhabricatorPolicyQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
     'PhabricatorPolicyRuleAdministrators' => 'PhabricatorPolicyRule',
     'PhabricatorPolicyRuleLunarPhase' => 'PhabricatorPolicyRule',
     'PhabricatorPolicyRuleProjects' => 'PhabricatorPolicyRule',
Index: src/applications/policy/application/PhabricatorApplicationPolicy.php
===================================================================
--- src/applications/policy/application/PhabricatorApplicationPolicy.php
+++ src/applications/policy/application/PhabricatorApplicationPolicy.php
@@ -15,7 +15,7 @@
       '/policy/' => array(
         'explain/(?P<phid>[^/]+)/(?P<capability>[^/]+)/'
           => 'PhabricatorPolicyExplainController',
-        'edit/' => 'PhabricatorPolicyEditController',
+        'edit/(?:(?P<phid>[^/]+)/)?' => 'PhabricatorPolicyEditController',
       ),
     );
   }
Index: src/applications/policy/controller/PhabricatorPolicyEditController.php
===================================================================
--- src/applications/policy/controller/PhabricatorPolicyEditController.php
+++ src/applications/policy/controller/PhabricatorPolicyEditController.php
@@ -3,32 +3,52 @@
 final class PhabricatorPolicyEditController
   extends PhabricatorPolicyController {
 
+  private $phid;
+
+  public function willProcessRequest(array $data) {
+    $this->phid = idx($data, 'phid');
+  }
+
   public function processRequest() {
     $request = $this->getRequest();
     $viewer = $request->getUser();
 
-    $policy = new PhabricatorPolicy();
-
-    $root_id = celerity_generate_unique_node_id();
-
     $action_options = array(
-      'allow' => pht('Allow'),
-      'deny' => pht('Deny'),
+      PhabricatorPolicy::ACTION_ALLOW => pht('Allow'),
+      PhabricatorPolicy::ACTION_DENY => pht('Deny'),
     );
 
     $rules = id(new PhutilSymbolLoader())
       ->setAncestorClass('PhabricatorPolicyRule')
       ->loadObjects();
-
     $rules = msort($rules, 'getRuleOrder');
 
-    $default_value = 'deny';
     $default_rule = array(
       'action' => head_key($action_options),
       'rule' => head_key($rules),
       'value' => null,
     );
 
+    if ($this->phid) {
+      $policies = id(new PhabricatorPolicyQuery())
+        ->setViewer($viewer)
+        ->withPHIDs(array($this->phid))
+        ->execute();
+      if (!$policies) {
+        return new Aphront404Response();
+      }
+      $policy = head($policies);
+    } else {
+      $policy = id(new PhabricatorPolicy())
+        ->setRules(array($default_rule))
+        ->setDefaultAction(PhabricatorPolicy::ACTION_DENY);
+    }
+
+    $root_id = celerity_generate_unique_node_id();
+
+    $default_action = $policy->getDefaultAction();
+    $rule_data = $policy->getRules();
+
     if ($request->isFormPost()) {
       $data = $request->getStr('rules');
       $data = @json_decode($data, true);
@@ -63,21 +83,38 @@
         );
       }
 
-      $policy->setRules($rule_data);
-      $policy->setDefaultAction($request->getStr('default'));
-      $policy->save();
-
-      // TODO: Integrate with policy editors.
-      $id = $policy->getID();
-      throw new Exception("OK, saved policy {$id}!");
-    } else {
-      $rule_data = array(
-        $default_rule,
+      // NOTE: Policies are immutable once created, and we always create a new
+      // policy here. If we didn't, we would need to lock this endpoint down,
+      // as users could otherwise just go edit the policies of objects with
+      // custom policies.
+
+      $new_policy = new PhabricatorPolicy();
+      $new_policy->setRules($rule_data);
+      $new_policy->setDefaultAction($request->getStr('default'));
+      $new_policy->save();
+
+      $data = array(
+        'phid' => $new_policy->getPHID(),
+        'info' => array(
+          'name' => $new_policy->getName(),
+          'full' => $new_policy->getName(),
+          'icon' => $new_policy->getIcon(),
+        ),
       );
+
+      return id(new AphrontAjaxResponse())->setContent($data);
+    }
+
+    // Convert rule values to display format (for example, expanding PHIDs
+    // into tokens).
+    foreach ($rule_data as $key => $rule) {
+      $rule_data[$key]['value'] = $rules[$rule['rule']]->getValueForDisplay(
+        $viewer,
+        $rule['value']);
     }
 
     $default_select = AphrontFormSelectControl::renderSelectTag(
-      $default_value,
+      $default_action,
       $action_options,
       array(
         'name' => 'default',
Index: src/applications/policy/rule/PhabricatorPolicyRuleUsers.php
===================================================================
--- src/applications/policy/rule/PhabricatorPolicyRuleUsers.php
+++ src/applications/policy/rule/PhabricatorPolicyRuleUsers.php
@@ -38,6 +38,10 @@
   }
 
   public function getValueForDisplay(PhabricatorUser $viewer, $value) {
+    if (!$value) {
+      return array();
+    }
+
     $handles = id(new PhabricatorHandleQuery())
       ->setViewer($viewer)
       ->withPHIDs($value)