I think that its dependent on the lies in question. Are they large lies? Or omissions? How badly do these lies affect you? Are you 100% sure they are lies?

Basically you have 3 options. The first one would be to let it go. If its mundane then it may be best to leave it alone. Is it worth killing the friendship over something small?

The other option is to walk away, depending on how severe the lies are. If these are things that can deeply affect you, then you are better off without that kind of distrust.

The third option, and maybe (imho) the best one, confront him. Lay all the cards on the table. Explain to him that you cherish him as a friend and you just want to get everything in the open. His reaction to you being honest as a friend is going to determine the best course of action to take next. Hope this helps.