diff --git a/docs/devel/testing.rst b/docs/devel/testing.rst
index 01e1919873..8ebcf85a31 100644
--- a/docs/devel/testing.rst
+++ b/docs/devel/testing.rst
@@ -240,6 +240,12 @@ a failing test:
   If the ``-gdb`` option is not used, ``$GDB_OPTIONS`` is ignored,
   regardless of whether it is set or not.
 
+* ``-valgrind`` attaches a valgrind instance to QEMU. If it detects
+  warnings, it will print and save the log in
+  ``$TEST_DIR/<valgrind_pid>.valgrind``.
+  The final command line will be ``valgrind --log-file=$TEST_DIR/
+  <valgrind_pid>.valgrind --error-exitcode=99 $QEMU ...``
+
 * ``-d`` (debug) just increases the logging verbosity, showing
   for example the QMP commands and answers.