Ability to set data-max relative to current date in datepicker

Right now it appears that it is not possible to set the data-max attribute to anything else than hard-coded dates (I could be wrong, of course). A nice enhancement would be to be able to set the max date a certain period of time into the future, relative to the current date. I imagine examples of data-max values like +1month, +1year so that all dates past that period of time will be disabled. 
