Lol nothing. Sorry, I mean you can stack all the most popular "miracle memory pill" nootropics you want up with prescription amphetamine or a wakefulness promoter like modafinil, fancy xanthines (caffeine on steroids), or even actual anabolic steroids, all of which folks have claimed are the real life "limitless pill." Marketing bullshit and unsubstantiated hype is all that is.
The closest I've come, meaning a regimen which is superior for achieving optimal brain function, is a good diet and vigorous exercise, along with adderall or another stimulant, and maybe throw in a nootropic like phenylpiracetam or adrafinil which happens to be a wakefulness promoter analogue or prodrug (I forget) of modafinil or maybe armodafinil, which are prescription only. The obvious cheat for instant effects is methamphetamine. You won't actually be smarter, but you'll damn sure think you are. And if you need to you'll get shit done. It's just that your performance may not be of the quality you believe it to be at the time you're doing it.
Edit: Microdosing with LSD or psilocybin, either by itself or in conjunction with whatever regimen you choose, might actually allow you to turn your brain on and become more attuned in general. May be something to consider. I've not tried microdosing so I can't speak from experience... Took a couple hundred ug's of some LSD last week though and the shift in consciousness and perception has been marked and very positive, as it usually is for me.
At least when it comes to IQ you're pretty much stuck with what you have, there are plenty of ways to reduce it though. 
