At both of the companies I've worked at we got a yearly "merit-based" increase depending on how your manager ranks you vs. your peers. The increase is anywhere from 0-5%, and the manager can only recommend their top employees for the high (5%) merit-based increases. This is on top of other increases (such as promotion-based increases), btw. I've gotten several pretty high merit-based increases back-to-back, and those +5% really start to compound with other forms of increase (promotions, bonuses, etc) after a few years.
If you were paid by "merit", you would be paid by your contribution to the revenue of the company. That is mostly restricted to owners.
Your output determines your merit and thus your pay, subject to random inaccuracies.