I only played him a few times and I have been getting the standard wriggles. I know he has innate sustain, but it costs mana and I would rather just use my mana on Q spam or ganks. Also when he has low HP it is hilarious to see him destroy a camp in seconds. The sustain is nice regardless to keep near full hp constantly, and I like it because it is cheap. So while slot inifficient, I rarely build 6 items as it is.
Ancient golem doesn't seem bad, the HP is awesome and the tenacity, although armor is a slightly less wanted stat now. With tenacity, you can get CDR boots.
Elder lizard has the CDR you want, but AD isn't exactly olaf's best stat. Not BAD mind you, but IMO it is on the bottom of the list. The passive doesn't seem to work too well, more of someone who has good AOE. Olaf's axes hit multiple people but you generally just stick to one target. I just it might be good because he IS spammy between the axes and E, but I think people like Hearim or maybe Riven would make better work of this.
There are better items than Golem to get hp/armor from. CDR takes specific items to itemize for and 40% cdr is VERY strong on Olaf. You probably won't upgrade your Spirit Stone until you hit 6 items, but when you do upgrade your ss as your sixth item you'd probably go Lizard unless you already have 40% cdr somehow.