  We study the covariant entropy bound in the context of gravitational
collapse. First, we discuss critically the heuristic arguments advanced by
Bousso. Then we solve the problem through an exact model: a Tolman-Bondi dust
shell collapsing into a Schwarzschild black hole. After the collapse, a new
black hole with a larger mass is formed. The horizon, $L$, of the old black
hole then terminates at the singularity. We show that the entropy crossing $L$
does not exceed a quarter of the area of the old horizon. Therefore, the
covariant entropy bound is satisfied in this process.
