How to ask drush to add timestamps to output? Some of the steps in our drush-make process take a while and having timestamps in the build-log would be useful -- for every line.

Is there a way to do this already, perhaps? The DRUSH_BACKEND pieces of JSON contain timestamps (seconds since Unix epoch), but they aren't shown for every step. Perhaps, there is something like a --timestamp flag in drush already?
It doesn't look this is possible. There is a list of available commands for drush make here: http://www.drushcommands.com/drush-7x/make/make