Apple: 12" rMB previous or current gen, 13"/15" rMBP current gen.

Other: Alienware, Dell, HP, etc all have laptops doing it. I don't have the link handy that lists ten windows laptops supporting it last Spring, but I'm sure Google can find it for you and there's likely dozens more now.

Ironically the MBP 2016 is probably the best for DP alternate mode over USB-C - thus far it's just worked for me on 3 different monitors.

HDMI you should just give up on though...