Nasus is overbearing? Counter-build him.

You're not building to counter him. Nasus's laning strength doesn't come from empowered Q's, withers, spamming his E.

Nasus's laning strength is based on his PASSIVE, and his HP returns from his R, to keep him in lane so he can continue to farm 25MP Q's.

You want to win a match against him? Stop following the exact same build every game.

1. Assess your build.
2. Find your first item, and select the most useful part of it.
3. When fighting a Nasus, build that item, and then DO NOT CONTINUE ON YOUR BUILD.
4. 
5. Return to your standard build.

And that's it. You don't even have to fully upgrade . Literally just keep it until you need the space, and sell it. Late game Nasus relies less on his heals, and more on his overall tankiness.