Using forms based logon for multiple site collections

Hi All,

I run a multitenanted SP2013 environment (with Office Web Apps but I doubt that matters here).

As it's multitenanted lots of different customers share the same web app but have an individual different site collection, with their own URL.

I was wondering if there was a way to setup Forms based login for a generic URL - something like xyz.com that points to the login form, then have that form intelligently work out where to send the user based on their logon account.

Sounds like something that might require dev work with a special front end but I thought I'd ask in here first in case this was something that can be done out of the box.

Thanks

Tom