diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -998,6 +998,7 @@
     'MacroCreateMemeConduitAPIMethod' => 'applications/macro/conduit/MacroCreateMemeConduitAPIMethod.php',
     'MacroQueryConduitAPIMethod' => 'applications/macro/conduit/MacroQueryConduitAPIMethod.php',
     'ManiphestAssignEmailCommand' => 'applications/maniphest/command/ManiphestAssignEmailCommand.php',
+    'ManiphestAssigneeDatasource' => 'applications/maniphest/typeahead/ManiphestAssigneeDatasource.php',
     'ManiphestBatchEditController' => 'applications/maniphest/controller/ManiphestBatchEditController.php',
     'ManiphestBulkEditCapability' => 'applications/maniphest/capability/ManiphestBulkEditCapability.php',
     'ManiphestClaimEmailCommand' => 'applications/maniphest/command/ManiphestClaimEmailCommand.php',
@@ -1031,6 +1032,8 @@
     'ManiphestInfoConduitAPIMethod' => 'applications/maniphest/conduit/ManiphestInfoConduitAPIMethod.php',
     'ManiphestNameIndex' => 'applications/maniphest/storage/ManiphestNameIndex.php',
     'ManiphestNameIndexEventListener' => 'applications/maniphest/event/ManiphestNameIndexEventListener.php',
+    'ManiphestNoOwnerDatasource' => 'applications/maniphest/typeahead/ManiphestNoOwnerDatasource.php',
+    'ManiphestOwnerDatasource' => 'applications/maniphest/typeahead/ManiphestOwnerDatasource.php',
     'ManiphestPriorityEmailCommand' => 'applications/maniphest/command/ManiphestPriorityEmailCommand.php',
     'ManiphestQueryConduitAPIMethod' => 'applications/maniphest/conduit/ManiphestQueryConduitAPIMethod.php',
     'ManiphestQueryStatusesConduitAPIMethod' => 'applications/maniphest/conduit/ManiphestQueryStatusesConduitAPIMethod.php',
@@ -2639,8 +2642,6 @@
     'PhabricatorTypeaheadInvalidTokenException' => 'applications/typeahead/exception/PhabricatorTypeaheadInvalidTokenException.php',
     'PhabricatorTypeaheadModularDatasourceController' => 'applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php',
     'PhabricatorTypeaheadMonogramDatasource' => 'applications/typeahead/datasource/PhabricatorTypeaheadMonogramDatasource.php',
-    'PhabricatorTypeaheadNoOwnerDatasource' => 'applications/typeahead/datasource/PhabricatorTypeaheadNoOwnerDatasource.php',
-    'PhabricatorTypeaheadOwnerDatasource' => 'applications/typeahead/datasource/PhabricatorTypeaheadOwnerDatasource.php',
     'PhabricatorTypeaheadResult' => 'applications/typeahead/storage/PhabricatorTypeaheadResult.php',
     'PhabricatorTypeaheadRuntimeCompositeDatasource' => 'applications/typeahead/datasource/PhabricatorTypeaheadRuntimeCompositeDatasource.php',
     'PhabricatorTypeaheadTokenView' => 'applications/typeahead/view/PhabricatorTypeaheadTokenView.php',
@@ -4270,6 +4271,7 @@
     'MacroCreateMemeConduitAPIMethod' => 'MacroConduitAPIMethod',
     'MacroQueryConduitAPIMethod' => 'MacroConduitAPIMethod',
     'ManiphestAssignEmailCommand' => 'ManiphestEmailCommand',
+    'ManiphestAssigneeDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'ManiphestBatchEditController' => 'ManiphestController',
     'ManiphestBulkEditCapability' => 'PhabricatorPolicyCapability',
     'ManiphestClaimEmailCommand' => 'ManiphestEmailCommand',
@@ -4304,6 +4306,8 @@
     'ManiphestInfoConduitAPIMethod' => 'ManiphestConduitAPIMethod',
     'ManiphestNameIndex' => 'ManiphestDAO',
     'ManiphestNameIndexEventListener' => 'PhabricatorEventListener',
+    'ManiphestNoOwnerDatasource' => 'PhabricatorTypeaheadDatasource',
+    'ManiphestOwnerDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'ManiphestPriorityEmailCommand' => 'ManiphestEmailCommand',
     'ManiphestQueryConduitAPIMethod' => 'ManiphestConduitAPIMethod',
     'ManiphestQueryStatusesConduitAPIMethod' => 'ManiphestConduitAPIMethod',
@@ -6053,8 +6057,6 @@
     'PhabricatorTypeaheadInvalidTokenException' => 'Exception',
     'PhabricatorTypeaheadModularDatasourceController' => 'PhabricatorTypeaheadDatasourceController',
     'PhabricatorTypeaheadMonogramDatasource' => 'PhabricatorTypeaheadDatasource',
-    'PhabricatorTypeaheadNoOwnerDatasource' => 'PhabricatorTypeaheadDatasource',
-    'PhabricatorTypeaheadOwnerDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'PhabricatorTypeaheadRuntimeCompositeDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'PhabricatorTypeaheadTokenView' => 'AphrontTagView',
     'PhabricatorTypeaheadUserParameterizedDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
diff --git a/src/applications/maniphest/constants/ManiphestTaskOwner.php b/src/applications/maniphest/constants/ManiphestTaskOwner.php
--- a/src/applications/maniphest/constants/ManiphestTaskOwner.php
+++ b/src/applications/maniphest/constants/ManiphestTaskOwner.php
@@ -2,7 +2,6 @@
 
 final class ManiphestTaskOwner extends ManiphestConstants {
 
-  const OWNER_UP_FOR_GRABS = 'PHID-!!!!-UP-FOR-GRABS';
   const PROJECT_NO_PROJECT = 'PHID-!!!!-NO-PROJECT';
 
 }
diff --git a/src/applications/maniphest/controller/ManiphestBatchEditController.php b/src/applications/maniphest/controller/ManiphestBatchEditController.php
--- a/src/applications/maniphest/controller/ManiphestBatchEditController.php
+++ b/src/applications/maniphest/controller/ManiphestBatchEditController.php
@@ -86,7 +86,7 @@
     $projects_source = new PhabricatorProjectDatasource();
     $mailable_source = new PhabricatorMetaMTAMailableDatasource();
     $mailable_source->setViewer($viewer);
-    $owner_source = new PhabricatorTypeaheadOwnerDatasource();
+    $owner_source = new ManiphestAssigneeDatasource();
     $owner_source->setViewer($viewer);
 
     require_celerity_resource('maniphest-batch-editor');
@@ -265,7 +265,8 @@
             continue 2;
           }
           $value = head($value);
-          if ($value === ManiphestTaskOwner::OWNER_UP_FOR_GRABS) {
+          $no_owner = ManiphestNoOwnerDatasource::FUNCTION_TOKEN;
+          if ($value === ManiphestNoOwnerDatasource::FUNCTION_TOKEN) {
             $value = null;
           }
           break;
diff --git a/src/applications/maniphest/query/ManiphestTaskQuery.php b/src/applications/maniphest/query/ManiphestTaskQuery.php
--- a/src/applications/maniphest/query/ManiphestTaskQuery.php
+++ b/src/applications/maniphest/query/ManiphestTaskQuery.php
@@ -73,9 +73,11 @@
   }
 
   public function withOwners(array $owners) {
+    $no_owner = ManiphestNoOwnerDatasource::FUNCTION_TOKEN;
+
     $this->includeUnowned = false;
     foreach ($owners as $k => $phid) {
-      if ($phid == ManiphestTaskOwner::OWNER_UP_FOR_GRABS || $phid === null) {
+      if ($phid === $no_owner || $phid === null) {
         $this->includeUnowned = true;
         unset($owners[$k]);
         break;
diff --git a/src/applications/maniphest/query/ManiphestTaskSearchEngine.php b/src/applications/maniphest/query/ManiphestTaskSearchEngine.php
--- a/src/applications/maniphest/query/ManiphestTaskSearchEngine.php
+++ b/src/applications/maniphest/query/ManiphestTaskSearchEngine.php
@@ -49,8 +49,6 @@
       'assignedPHIDs',
       $this->readUsersFromRequest($request, 'assigned'));
 
-    $saved->setParameter('withUnassigned', $request->getBool('withUnassigned'));
-
     $saved->setParameter(
       'authorPHIDs',
       $this->readUsersFromRequest($request, 'authors'));
@@ -139,14 +137,13 @@
       $query->withSubscribers($subscriber_phids);
     }
 
-    $with_unassigned = $saved->getParameter('withUnassigned');
-    if ($with_unassigned) {
-      $query->withOwners(array(null));
-    } else {
-      $assigned_phids = $saved->getParameter('assignedPHIDs', array());
-      if ($assigned_phids) {
-        $query->withOwners($assigned_phids);
-      }
+    $datasource = id(new ManiphestOwnerDatasource())
+      ->setViewer($this->requireViewer());
+
+    $assigned_phids = $this->readAssignedPHIDs($saved);
+    $assigned_phids = $datasource->evaluateTokens($assigned_phids);
+    if ($assigned_phids) {
+      $query->withOwners($assigned_phids);
     }
 
     $statuses = $saved->getParameter('statuses');
@@ -242,7 +239,8 @@
     AphrontFormView $form,
     PhabricatorSavedQuery $saved) {
 
-    $assigned_phids = $saved->getParameter('assignedPHIDs', array());
+    $assigned_phids = $this->readAssignedPHIDs($saved);
+
     $author_phids = $saved->getParameter('authorPHIDs', array());
     $all_project_phids = $saved->getParameter(
       'allProjectPHIDs',
@@ -258,7 +256,6 @@
       array());
     $subscriber_phids = $saved->getParameter('subscriberPHIDs', array());
 
-    $with_unassigned = $saved->getParameter('withUnassigned');
     $with_no_projects = $saved->getParameter('withNoProject');
 
     $statuses = $saved->getParameter('statuses', array());
@@ -314,17 +311,10 @@
     $form
       ->appendControl(
         id(new AphrontFormTokenizerControl())
-          ->setDatasource(new PhabricatorPeopleDatasource())
+          ->setDatasource(new ManiphestOwnerDatasource())
           ->setName('assigned')
           ->setLabel(pht('Assigned To'))
           ->setValue($assigned_phids))
-      ->appendChild(
-        id(new AphrontFormCheckboxControl())
-          ->addCheckbox(
-            'withUnassigned',
-            1,
-            pht('Show only unassigned tasks.'),
-            $with_unassigned))
       ->appendControl(
         id(new AphrontFormTokenizerControl())
           ->setDatasource(new PhabricatorProjectDatasource())
@@ -563,4 +553,17 @@
       ->setShowBatchControls($this->showBatchControls);
   }
 
+  private function readAssignedPHIDs(PhabricatorSavedQuery $saved) {
+    $assigned_phids = $saved->getParameter('assignedPHIDs', array());
+
+    // This may be present in old saved queries from before parameterized
+    // typeaheads, and is retained for compatibility. We could remove it by
+    // migrating old saved queries.
+    if ($saved->getParameter('withUnassigned')) {
+      $assigned_phids[] = ManiphestNoOwnerDatasource::FUNCTION_TOKEN;
+    }
+
+    return $assigned_phids;
+  }
+
 }
diff --git a/src/applications/typeahead/datasource/PhabricatorTypeaheadOwnerDatasource.php b/src/applications/maniphest/typeahead/ManiphestAssigneeDatasource.php
rename from src/applications/typeahead/datasource/PhabricatorTypeaheadOwnerDatasource.php
rename to src/applications/maniphest/typeahead/ManiphestAssigneeDatasource.php
--- a/src/applications/typeahead/datasource/PhabricatorTypeaheadOwnerDatasource.php
+++ b/src/applications/maniphest/typeahead/ManiphestAssigneeDatasource.php
@@ -1,20 +1,20 @@
 <?php
 
-final class PhabricatorTypeaheadOwnerDatasource
+final class ManiphestAssigneeDatasource
   extends PhabricatorTypeaheadCompositeDatasource {
 
   public function getBrowseTitle() {
-    return pht('Browse Owners');
+    return pht('Browse Assignees');
   }
 
   public function getPlaceholderText() {
-    return pht('Type a user name or "none"...');
+    return pht('Type a username or "none"...');
   }
 
   public function getComponentDatasources() {
     return array(
       new PhabricatorPeopleDatasource(),
-      new PhabricatorTypeaheadNoOwnerDatasource(),
+      new ManiphestNoOwnerDatasource(),
     );
   }
 
diff --git a/src/applications/maniphest/typeahead/ManiphestNoOwnerDatasource.php b/src/applications/maniphest/typeahead/ManiphestNoOwnerDatasource.php
new file mode 100644
--- /dev/null
+++ b/src/applications/maniphest/typeahead/ManiphestNoOwnerDatasource.php
@@ -0,0 +1,64 @@
+<?php
+
+final class ManiphestNoOwnerDatasource
+  extends PhabricatorTypeaheadDatasource {
+
+  const FUNCTION_TOKEN = 'none()';
+
+  public function getBrowseTitle() {
+    return pht('Browse No Owner');
+  }
+
+  public function getPlaceholderText() {
+    return pht('Type "none"...');
+  }
+
+  public function getDatasourceApplicationClass() {
+    return 'PhabricatorManiphestApplication';
+  }
+
+  public function getDatasourceFunctions() {
+    return array(
+      'none' => array(
+        'name' => pht('Find results which are not assigned.'),
+      ),
+    );
+  }
+
+  public function loadResults() {
+    $results = array(
+      $this->buildNoOwnerResult(),
+    );
+    return $this->filterResultsAgainstTokens($results);
+  }
+
+  protected function evaluateFunction($function, array $argv_list) {
+    $results = array();
+
+    foreach ($argv_list as $argv) {
+      $results[] = self::FUNCTION_TOKEN;
+    }
+
+    return $results;
+  }
+
+  public function renderFunctionTokens($function, array $argv_list) {
+    $results = array();
+    foreach ($argv_list as $argv) {
+      $results[] = PhabricatorTypeaheadTokenView::newFromTypeaheadResult(
+        $this->buildNoOwnerResult());
+    }
+    return $results;
+  }
+
+  private function buildNoOwnerResult() {
+    $name = pht('No Owner');
+    return $this->newFunctionResult()
+      ->setName($name.' none')
+      ->setDisplayName($name)
+      ->setIcon('fa-ban')
+      ->setPHID('none()')
+      ->setUnique(true);
+  }
+
+}
diff --git a/src/applications/typeahead/datasource/PhabricatorTypeaheadOwnerDatasource.php b/src/applications/maniphest/typeahead/ManiphestOwnerDatasource.php
rename from src/applications/typeahead/datasource/PhabricatorTypeaheadOwnerDatasource.php
rename to src/applications/maniphest/typeahead/ManiphestOwnerDatasource.php
--- a/src/applications/typeahead/datasource/PhabricatorTypeaheadOwnerDatasource.php
+++ b/src/applications/maniphest/typeahead/ManiphestOwnerDatasource.php
@@ -1,6 +1,6 @@
 <?php
 
-final class PhabricatorTypeaheadOwnerDatasource
+final class ManiphestOwnerDatasource
   extends PhabricatorTypeaheadCompositeDatasource {
 
   public function getBrowseTitle() {
@@ -8,13 +8,15 @@
   }
 
   public function getPlaceholderText() {
-    return pht('Type a user name or "none"...');
+    return pht('Type a username or function...');
   }
 
   public function getComponentDatasources() {
     return array(
+      new PhabricatorViewerDatasource(),
+      new ManiphestNoOwnerDatasource(),
       new PhabricatorPeopleDatasource(),
-      new PhabricatorTypeaheadNoOwnerDatasource(),
+      new PhabricatorProjectMembersDatasource(),
     );
   }
 
diff --git a/src/applications/search/query/PhabricatorSearchApplicationSearchEngine.php b/src/applications/search/query/PhabricatorSearchApplicationSearchEngine.php
--- a/src/applications/search/query/PhabricatorSearchApplicationSearchEngine.php
+++ b/src/applications/search/query/PhabricatorSearchApplicationSearchEngine.php
@@ -126,7 +126,7 @@
         id(new AphrontFormTokenizerControl())
           ->setName('ownerPHIDs')
           ->setLabel('Owners')
-          ->setDatasource(new PhabricatorTypeaheadOwnerDatasource())
+          ->setDatasource(new ManiphestOwnerDatasource())
           ->setValue($owner_phids))
       ->appendChild(
         id(new AphrontFormCheckboxControl())
diff --git a/src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php b/src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php
--- a/src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php
+++ b/src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php
@@ -247,8 +247,7 @@
     // format to make it easier to debug typeahead output.
 
     foreach ($sources as $key => $source) {
-      // This can happen with composite sources like user or project, as well
-      // generic ones like NoOwner
+      // This can happen with composite or generic sources.
       if (!$source->getDatasourceApplicationClass()) {
         continue;
       }
diff --git a/src/applications/typeahead/datasource/PhabricatorTypeaheadNoOwnerDatasource.php b/src/applications/typeahead/datasource/PhabricatorTypeaheadNoOwnerDatasource.php
deleted file mode 100644
--- a/src/applications/typeahead/datasource/PhabricatorTypeaheadNoOwnerDatasource.php
+++ /dev/null
@@ -1,32 +0,0 @@
-<?php
-
-final class PhabricatorTypeaheadNoOwnerDatasource
-  extends PhabricatorTypeaheadDatasource {
-
-  public function getBrowseTitle() {
-    return pht('Browse No Owner');
-  }
-
-  public function getPlaceholderText() {
-    return pht('Type "none"...');
-  }
-
-  public function getDatasourceApplicationClass() {
-    return null;
-  }
-
-  public function loadResults() {
-    $viewer = $this->getViewer();
-    $raw_query = $this->getRawQuery();
-
-    $results = array();
-
-    $results[] = id(new PhabricatorTypeaheadResult())
-      ->setName(pht('None'))
-      ->setIcon('fa-ban orange')
-      ->setPHID(ManiphestTaskOwner::OWNER_UP_FOR_GRABS);
-
-    return $results;
-  }
-
-}