diff --git a/src/applications/cache/PhabricatorCaches.php b/src/applications/cache/PhabricatorCaches.php
--- a/src/applications/cache/PhabricatorCaches.php
+++ b/src/applications/cache/PhabricatorCaches.php
@@ -117,6 +117,42 @@
   }
 
 
+/* -(  Runtime Cache  )------------------------------------------------------ */
+
+
+  /**
+   * Get a runtime cache stack.
+   *
+   * This stack is just APC. It's fast, it's effectively immutable, and it
+   * gets thrown away when the webserver restarts.
+   *
+   * This cache is suitable for deriving runtime caches, like a map of Conduit
+   * method names to provider classes.
+   *
+   * @return PhutilKeyValueCacheStack Best runtime stack available.
+   */
+  public static function getRuntimeCache() {
+    static $cache;
+    if (!$cache) {
+      $caches = self::buildRuntimeCaches();
+      $cache = self::newStackFromCaches($caches);
+    }
+    return $cache;
+  }
+
+
+  private static function buildRuntimeCaches() {
+    $caches = array();
+
+    $apc = new PhutilAPCKeyValueCache();
+    if ($apc->isAvailable()) {
+      $caches[] = $apc;
+    }
+
+    return $caches;
+  }
+
+
 /* -(  Repository Graph Cache  )--------------------------------------------- */