Sly's 8-bedroom, 9-bath Beverly Hills mansion is back on the market with the same sticker price he slapped on it a few months ago -- he's asking $85 mil for the sweet pad ... one he's long called home since snapping it up in the '90s.

He'd initially listed it in February at $110 mil ... but we're told no one was biting at the time, so he slashed the price by a lot -- some $25 mil or so to get it at its current price. Sly didn't have any takers at the time -- so he yanked it off the market.

But, things have changed. The real estate market in SoCal is hotter than ever, and houses in gated communities are going at a premium. So, this time around ... it's a very good bet someone's gonna scoop it up.

Whoever buys this puppy is gonna have a whole lot of room to spread out -- the house sits on over 3 acres of land. It's quite literally a palace ... a custom one at that which SS himself made to his liking, and which is essentially a shrine to his 'Rocky' legacy.

We don't think any of that stuff is gonna stay, but whatever is studs-in certainly will ... including every awesome thing the property offers. For example, there's an 8-car garage, an art studio, a sauna and steam room, an infinity pool, a private theater, a gym ... and a cigar room, just to name a few of the perks of shelling out. Plus ... Sylvester himself lived there!

Sly, Jennifer and the kids have left La La Land for good. They're now ensconced in Florida -- like a lot of other celebs -- and he's just trying to shed the last of his compounds here. Step right up ... come and take on the champ, if you can afford it.