How to set up CSS/JS cache busting using PHP and Git on high traffic site?

How to set up CSS/JS cache busting using PHP and Git on high traffic site?

I need to set up cache busting for CSS/JS on a high traffic site that uses
PHP and Git.
I know how to get the current Git version using "git describe --tags
--always". I need to do this so PHP will cache this value and only run
every 5 minutes or so. How can this be done?