The facts matter so it's tough to advise without knowing them all but as general rule, as long as the overstay was for less than 6 months, you should be able to adjust status in the U.S.
I'm not the expert here, but AOS only applies when you're currently in the US. Has this person been in the US for over a decade without a valid status?
Currently in the US. Reentered US again after visa overstay and maintained valid status since then. Current employee is planning to apply for H-1B next year. Although prior overstay length is < 180 days - the worry is still there.