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
@@ -419,6 +419,7 @@
     'phutil_console_prompt' => 'console/format.php',
     'phutil_console_require_tty' => 'console/format.php',
     'phutil_console_wrap' => 'console/format.php',
+    'phutil_count' => 'internationalization/pht.php',
     'phutil_date_format' => 'utils/viewutils.php',
     'phutil_deprecated' => 'moduleutils/moduleutils.php',
     'phutil_error_listener_example' => 'error/phlog.php',
diff --git a/src/internationalization/pht.php b/src/internationalization/pht.php
--- a/src/internationalization/pht.php
+++ b/src/internationalization/pht.php
@@ -16,3 +16,18 @@
   $translator = PhutilTranslator::getInstance();
   return call_user_func_array(array($translator, 'translate'), $args);
 }
+
+/**
+ * Count all elements in an array, or something in an object.
+ *
+ * @param  array|Countable  A countable object.
+ * @return PhutilNumber     Returns the number of elements in the input
+ *                          parameter.
+ */
+function phutil_count($countable) {
+  if (!(is_array($countable) || $countable instanceof Countable)) {
+    throw new InvalidArgumentException(pht('Argument should be countable.'));
+  }
+
+  return new PhutilNumber(count($countable));
+}