Yep. Add the source address (or some more specific yet easily computed identifier) to a table that is checked early in the network path (in hardware if possible).

Or, if you want to be fancy, "tarpit" them (complete TCP handshake and then ignore, forcing attacker to actually commit resources), but apparently that's of questionable value these days. [1]

[1] https://en.wikipedia.org/wiki/Tarpit_(networking)