Suppose, in the future, an alien species (I'll refer to them as the Destroyers) develops an extreme dislike for humanity. The Destroyers track human ships back to Earth and take actions that lead to the extermination of all life on Earth, as well as rendering the Earth unfit for human habitation. Over the following years, Earth is forgotten by humanity until, thousands of years later, it is rediscovered.
The catch is, they weren't the first to arrive.
Another alien species (I'll refer to them as the Rebuilders) long since discovered Earth. The Rebuilders decided to restore the Earth to a habitable state and seed new life, mostly to prove they can, but also to bolster their god complex. To accomplish this, the Rebuilders harvested material from the other celestial bodies in the Solar System and set to work terraforming Earth to their specifications.
How reasonable is this scenario? Are there sufficient materials in the Solar System to restore a barren, rocky Earth devoid of an atmosphere to a lush, green-and-blue pearl of a planet complete with complex life? How much of those resources would need to be consumed to rejuvenate the Earth?
Note that I am not asking about a reasonable timeframe for evolution to produce complex lifeforms; this can be taken care of by the Rebuilders' hyper-advanced technology and/or handwavium (which is pretty much the same thing).