No, that's incorrect. For example, here's a law from Minnesota that explicitly states you may exceed the posted speed limit by up to 10 mph when passing:

Subd. 2a.Increased speed limit when passing.

Notwithstanding subdivision 2, the speed limit is increased by ten miles per hour over the posted speed limit when the driver:

(1) is on a two-lane highway having one lane for each direction of travel;

(2) is on a highway with a posted speed limit that is equal to or higher than 55 miles per hour;

(3) is overtaking and passing another vehicle proceeding in the same direction of travel; and

(4) meets the requirements in section 169.18.