diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index dca89eceeda98a..6a60bc4954c625 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -100,6 +100,11 @@ source.
    first element will be set to ``"-m"``). As with the :option:`-c` option,
    the current directory will be added to the start of :data:`sys.path`.
 
+   :option:`-I` option can  be used to run the script in isolated mode where
+   :data:`sys.path` contains neither the current directory nor the user's
+   site-packages directory. All :envvar:`PYTHON*` environment variables are
+   ignored, too.
+
    Many standard library modules contain code that is invoked on their execution
    as a script.  An example is the :mod:`timeit` module::
 
@@ -119,6 +124,7 @@ source.
    .. versionchanged:: 3.4
       namespace packages are also supported
 
+.. _cmdarg-dash:
 
 .. describe:: -
 
@@ -130,6 +136,8 @@ source.
    :data:`sys.path`.
 
 
+.. _cmdarg-script:
+
 .. describe:: <script>
 
    Execute the Python code contained in *script*, which must be a filesystem
@@ -148,6 +156,11 @@ source.
    added to the start of :data:`sys.path` and the ``__main__.py`` file in
    that location is executed as the :mod:`__main__` module.
 
+   :option:`-I` option can  be used to run the script in isolated mode where
+   :data:`sys.path` contains neither the script's directory nor the user's
+   site-packages directory. All :envvar:`PYTHON*` environment variables are
+   ignored, too.
+
    .. seealso::
       :func:`runpy.run_path`
          Equivalent functionality directly available to Python code