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
@@ -113,17 +113,49 @@
         $this->requireResource('typeahead-browse-css');
         $this->initBehavior('typeahead-browse');
 
-        $markup = phutil_tag(
+        $input_id = celerity_generate_unique_node_id();
+        $frame_id = celerity_generate_unique_node_id();
+
+        $config = array(
+          'inputID' => $input_id,
+          'frameID' => $frame_id,
+          'uri' => (string)$request->getRequestURI(),
+        );
+        $this->initBehavior('typeahead-search', $config);
+
+        $search = javelin_tag(
+          'input',
+          array(
+            'type' => 'text',
+            'id' => $input_id,
+            'class' => 'typeahead-browse-input',
+            'autocomplete' => 'off',
+            'placeholder' => $source->getPlaceholderText(),
+          ));
+
+        $frame = phutil_tag(
           'div',
           array(
             'class' => 'typeahead-browse-frame',
+            'id' => $frame_id,
           ),
           $markup);
 
+        $browser = array(
+          phutil_tag(
+            'div',
+            array(
+              'class' => 'typeahead-browse-header',
+            ),
+            $search),
+          $frame,
+        );
+
         return $this->newDialog()
           ->setWidth(AphrontDialogView::WIDTH_FORM)
+          ->setRenderDialogAsDiv(true)
           ->setTitle(get_class($source)) // TODO: Provide nice names.
-          ->appendChild($markup)
+          ->appendChild($browser)
           ->addCancelButton('/', pht('Close'));
       }
 
diff --git a/webroot/rsrc/css/aphront/typeahead-browse.css b/webroot/rsrc/css/aphront/typeahead-browse.css
--- a/webroot/rsrc/css/aphront/typeahead-browse.css
+++ b/webroot/rsrc/css/aphront/typeahead-browse.css
@@ -32,3 +32,16 @@
   height: 260px;
   border: 1px solid {$lightgreyborder};
 }
+
+.typeahead-browse-frame.loading {
+  opacity: 0.8;
+}
+
+.typeahead-browse-header {
+  padding: 4px 0;
+}
+
+input.typeahead-browse-input {
+  margin: 0;
+  width: 100%;
+}
diff --git a/webroot/rsrc/js/application/typeahead/behavior-typeahead-search.js b/webroot/rsrc/js/application/typeahead/behavior-typeahead-search.js
new file mode 100644
--- /dev/null
+++ b/webroot/rsrc/js/application/typeahead/behavior-typeahead-search.js
@@ -0,0 +1,56 @@
+/**
+ * @provides javelin-behavior-typeahead-search
+ * @requires javelin-behavior
+ *           javelin-stratcom
+ *           javelin-workflow
+ *           javelin-dom
+ */
+
+JX.behavior('typeahead-search', function(config) {
+  var input = JX.$(config.inputID);
+  var frame = JX.$(config.frameID);
+  var last = input.value;
+
+  function update() {
+    if (input.value == last) {
+      // This is some kind of non-input keypress like an arrow key. Don't
+      // send a query to the server.
+      return;
+    }
+
+    // Call load() in a little while. If the user hasn't typed anything else,
+    // we'll send a request to get results.
+    setTimeout(JX.bind(null, load, input.value), 100);
+  }
+
+  function load(value) {
+    if (value != input.value) {
+      // The user has typed some more text, so don't send a request yet. We
+      // want to wait for them to stop typing.
+      return;
+    }
+
+    JX.DOM.alterClass(frame, 'loading', true);
+    new JX.Workflow(config.uri, {q: value})
+      .setHandler(function(r) {
+        if (value != input.value) {
+          // The user typed some more stuff while the request was in flight,
+          // so ignore the response.
+          return;
+        }
+
+        last = input.value;
+        JX.DOM.setContent(frame, JX.$H(r.markup));
+        JX.DOM.alterClass(frame, 'loading', false);
+      })
+      .start();
+  }
+
+  JX.DOM.listen(input, ['keydown', 'keypress', 'keyup'], null, function() {
+    // We need to delay this to actually read the value after the keypress.
+    setTimeout(update, 0);
+  });
+
+  JX.DOM.focus(input);
+
+});