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
@@ -489,6 +489,7 @@
     'DifferentialReleephRequestFieldSpecification' => 'applications/releeph/differential/DifferentialReleephRequestFieldSpecification.php',
     'DifferentialRemarkupRule' => 'applications/differential/remarkup/DifferentialRemarkupRule.php',
     'DifferentialReplyHandler' => 'applications/differential/mail/DifferentialReplyHandler.php',
+    'DifferentialRepositoryDatasource' => 'applications/differential/typeahead/DifferentialRepositoryDatasource.php',
     'DifferentialRepositoryField' => 'applications/differential/customfield/DifferentialRepositoryField.php',
     'DifferentialRepositoryLookup' => 'applications/differential/query/DifferentialRepositoryLookup.php',
     'DifferentialRequiredSignaturesField' => 'applications/differential/customfield/DifferentialRequiredSignaturesField.php',
@@ -818,6 +819,7 @@
     'DiffusionSymbolQuery' => 'applications/diffusion/query/DiffusionSymbolQuery.php',
     'DiffusionTagListController' => 'applications/diffusion/controller/DiffusionTagListController.php',
     'DiffusionTagListView' => 'applications/diffusion/view/DiffusionTagListView.php',
+    'DiffusionTaggedRepositoriesFunctionDatasource' => 'applications/diffusion/typeahead/DiffusionTaggedRepositoriesFunctionDatasource.php',
     'DiffusionTagsQueryConduitAPIMethod' => 'applications/diffusion/conduit/DiffusionTagsQueryConduitAPIMethod.php',
     'DiffusionURIEditConduitAPIMethod' => 'applications/diffusion/conduit/DiffusionURIEditConduitAPIMethod.php',
     'DiffusionURIEditEngine' => 'applications/diffusion/editor/DiffusionURIEditEngine.php',
@@ -4706,6 +4708,7 @@
     'DifferentialReleephRequestFieldSpecification' => 'Phobject',
     'DifferentialRemarkupRule' => 'PhabricatorObjectRemarkupRule',
     'DifferentialReplyHandler' => 'PhabricatorApplicationTransactionReplyHandler',
+    'DifferentialRepositoryDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'DifferentialRepositoryField' => 'DifferentialCoreCustomField',
     'DifferentialRepositoryLookup' => 'Phobject',
     'DifferentialRequiredSignaturesField' => 'DifferentialCoreCustomField',
@@ -5052,6 +5055,7 @@
     'DiffusionSymbolQuery' => 'PhabricatorOffsetPagedQuery',
     'DiffusionTagListController' => 'DiffusionController',
     'DiffusionTagListView' => 'DiffusionView',
+    'DiffusionTaggedRepositoriesFunctionDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'DiffusionTagsQueryConduitAPIMethod' => 'DiffusionQueryConduitAPIMethod',
     'DiffusionURIEditConduitAPIMethod' => 'PhabricatorEditEngineAPIMethod',
     'DiffusionURIEditEngine' => 'PhabricatorEditEngine',
diff --git a/src/applications/differential/query/DifferentialRevisionSearchEngine.php b/src/applications/differential/query/DifferentialRevisionSearchEngine.php
--- a/src/applications/differential/query/DifferentialRevisionSearchEngine.php
+++ b/src/applications/differential/query/DifferentialRevisionSearchEngine.php
@@ -75,7 +75,7 @@
         ->setLabel(pht('Repositories'))
         ->setKey('repositoryPHIDs')
         ->setAliases(array('repository', 'repositories', 'repositoryPHID'))
-        ->setDatasource(new DiffusionRepositoryDatasource())
+        ->setDatasource(new DifferentialRepositoryDatasource())
         ->setDescription(
           pht('Find revisions from specific repositories.')),
       id(new PhabricatorSearchSelectField())
diff --git a/src/applications/differential/typeahead/DifferentialRepositoryDatasource.php b/src/applications/differential/typeahead/DifferentialRepositoryDatasource.php
new file mode 100644
--- /dev/null
+++ b/src/applications/differential/typeahead/DifferentialRepositoryDatasource.php
@@ -0,0 +1,25 @@
+<?php
+
+final class DifferentialRepositoryDatasource
+  extends PhabricatorTypeaheadCompositeDatasource {
+
+  public function getBrowseTitle() {
+    return pht('Browse Repositories');
+  }
+
+  public function getPlaceholderText() {
+    return pht('Type a repository name or function...');
+  }
+
+  public function getDatasourceApplicationClass() {
+    return 'PhabricatorDifferentialApplication';
+  }
+
+  public function getComponentDatasources() {
+    return array(
+      new DiffusionTaggedRepositoriesFunctionDatasource(),
+      new DiffusionRepositoryDatasource(),
+    );
+  }
+
+}
diff --git a/src/applications/diffusion/typeahead/DiffusionTaggedRepositoriesFunctionDatasource.php b/src/applications/diffusion/typeahead/DiffusionTaggedRepositoriesFunctionDatasource.php
new file mode 100644
--- /dev/null
+++ b/src/applications/diffusion/typeahead/DiffusionTaggedRepositoriesFunctionDatasource.php
@@ -0,0 +1,100 @@
+<?php
+
+final class DiffusionTaggedRepositoriesFunctionDatasource
+  extends PhabricatorTypeaheadCompositeDatasource {
+
+  public function getBrowseTitle() {
+    return pht('Browse Repositories');
+  }
+
+  public function getPlaceholderText() {
+    return pht('Type tagged(<project>)...');
+  }
+
+  public function getDatasourceApplicationClass() {
+    return 'PhabricatorProjectApplication';
+  }
+
+  public function getComponentDatasources() {
+    return array(
+      new PhabricatorProjectDatasource(),
+    );
+  }
+
+  public function getDatasourceFunctions() {
+    return array(
+      'repositories' => array(
+        'name' => pht('Repositories: ...'),
+        'arguments' => pht('project'),
+        'summary' => pht('Find results for repositories of a project.'),
+        'description' => pht(
+          'This function allows you to find results for any of the `.
+          `repositories of a project:'.
+          "\n\n".
+          '> projects'),
+      ),
+    );
+  }
+
+  protected function didLoadResults(array $results) {
+    foreach ($results as $result) {
+      $result
+        ->setTokenType(PhabricatorTypeaheadTokenView::TYPE_FUNCTION)
+        ->setColor(null)
+        ->setPHID('repositories('.$result->getPHID().')')
+        ->setDisplayName(pht('tagged: %s', $result->getDisplayName()))
+        ->setName($result->getName().' repositories');
+    }
+
+    return $results;
+  }
+
+  protected function evaluateFunction($function, array $argv_list) {
+    $phids = array();
+    foreach ($argv_list as $argv) {
+      $phids[] = head($argv);
+    }
+
+    $repositories = id(new PhabricatorRepositoryQuery())
+        ->setViewer($this->getViewer())
+        ->withEdgeLogicPHIDs(
+          PhabricatorProjectObjectHasProjectEdgeType::EDGECONST,
+          PhabricatorQueryConstraint::OPERATOR_OR,
+          $phids)
+        ->execute();
+
+    $results = array();
+
+    foreach ($repositories as $repository) {
+      $results[] = $repository->getPHID();
+    }
+
+    return $results;
+  }
+
+  public function renderFunctionTokens($function, array $argv_list) {
+    $phids = array();
+    foreach ($argv_list as $argv) {
+      $phids[] = head($argv);
+    }
+
+    $tokens = $this->renderTokens($phids);
+    foreach ($tokens as $token) {
+      // Remove any project color on this token.
+      $token->setColor(null);
+
+      if ($token->isInvalid()) {
+        $token
+          ->setValue(pht('Repositories: Invalid Project'));
+      } else {
+        $token
+          ->setTokenType(PhabricatorTypeaheadTokenView::TYPE_FUNCTION)
+          ->setKey('repositories('.$token->getKey().')')
+          ->setValue(pht('tagged: %s', $token->getValue()));
+      }
+    }
+
+    return $tokens;
+  }
+
+}