(NOTE: The damage in the preface is 181. The ACTUAL damage count should somewhere closer to 305.)
Master Banana build is probably the ****. We're gunna start with that.
But in detail, we can say this; YOU WILL NOT DIE. This is the build for the melee "nuker" who cares about dominating AND surviving team fights, as well as soloing like a champ Olaf player. This build allows you to utilize offensive masteries and runes instead of wasting those on your survivability.

x9 Greater Marks of Desolation: ARMOR PEN ARMOR PEN ARMOR PEN.
x9 Greater Seals of Evasion: Increasing your dodge chance by .75% per seal is good. Do the math.
x9 Greater Glyphs of Celerity: .9% cooldown reduction at level 18 per Glyph is good too, mixed with the CD reduction in the offensive mastery. I don't need to elaborate.

BERSERKER'S GREAVES: Good item to start with, necessary for movement speed, and escaping the inevitable gank.

BLOODTHIRSTER: Getting this item early will allow for survivability while laning, and intense early game damage for the skirmishes you'll enter while laning. Basically, get this early, and get fed early. Good start to any game.

FROZEN MALLET: This is the start to your survivability. The damage will come in handy, and the 700 or so health will too. This item, plus the Bloodthirster will put you ahead in pretty much any 1v1 fight, and the item's UNIQUE will help for when they try to run, even in teamfights.

RANDUIN'S OMEN: This item can be replaced by SPIRIT VISAGE or BANSHEE'S VEIL if the enemy team is caster heavy, or of you're gettin nuked like a baws. The armor (magic resistance) will again aid in survivability, allowing you to take more hits and survive the teamfight or gank you normally wouldn't have. The health is good for obvious reasons, but also because of ATMA'S passive. The more health you have, the more damage you do. The longer you live.

ATMA'S IMPALER: The crit is helpful, and the armor is helpful, but its the PASSIVE that makes this item worth the time. 2% of the user's maximum health is transferred into Attack Damage. That's good.

WARMOG'S ARMOR: This item adds a ****ton of health, keeping you alive, and in turn, adding a ****ton of damage.

These items are expensive, no doubt, but play like a good Pantheon and get fed. This build should take you about 40 in-game minutes to complete, and you will be easily unstoppable even well before its full.

PROS:
- Atma's will give incredible damage endgame.
- Very high survivability means you will be less likely to lose stacks on Bloodthirster.
- More leverage when Aegis of Zeonia or Grand Skyfall is used.
- Invincible 1v1, very useful in teamfights, and great for saving allies.
CONS:
- Pricey build.
- Lacks damage until Atma's is purchased.