Rachel McAdams Debuts Short New 'Do -- Like the Look?

Rachel McAdams has got herself a brand new 'do!

The former "Mean Girls" star was spotted on the set of her latest movie "About Time" today in London's Paddington Station -- where she was rocking much shorter locks.

We're not 100% sure if she chopped off her hair or if she's wearing a wig for the part.

Regardless, we want to know what you think of the new look.

Do you like the shoulder-length cut ... or do you prefer Rachel with a much longer mane?

Vote in the gallery above!