diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index 5fa5cfd9efdac74cd03ea97b9794cdc5713cbe0c..1c3aff68923768d9258c60af163e6981de836a57 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -831,6 +831,8 @@ QQmlEngine::QQmlEngine(QQmlEnginePrivate &dd, QObject *parent)
   Any QQmlContext's created on this engine will be
   invalidated, but not destroyed (unless they are parented to the
   QQmlEngine object).
+
+  See QJSEngine docs for details on cleaning up the JS engine.
 */
 QQmlEngine::~QQmlEngine()
 {
diff --git a/src/qml/qml/v8/qjsengine.cpp b/src/qml/qml/v8/qjsengine.cpp
index 5b1464afe676938377c71c171fd03c1f072c795f..dbd0851fec10fa246633a37234fcc428d60784b3 100644
--- a/src/qml/qml/v8/qjsengine.cpp
+++ b/src/qml/qml/v8/qjsengine.cpp
@@ -195,6 +195,10 @@ QJSEngine::QJSEngine(QJSEnginePrivate &dd, QObject *parent)
 
 /*!
     Destroys this QJSEngine.
+
+    Garbage is not collected from the persistent JS heap during QJSEngine
+    destruction. If you need all memory freed, call collectGarbage manually
+    right before destroying the QJSEngine.
 */
 QJSEngine::~QJSEngine()
 {