Change outgoing links... easy way?

I'm working on a site that has a bunch of outgoing links and the address
of the outgoing links has changed. The links go to various locations of
a single different site (www.website.com/index, www.website.com/contact,
www.website.com/products, etc.) They need to change to
(www.newwebsite.com/index, www.newwebsite.com/contact,
www.newwebsite.com/products, etc.), same html pages, different domain.

Is there a way to change all of those url's without going to each and
every link and changing them manually?

-grant