D&D arcane magic is inspired by Vance, at best. . .
In Vance's The Dying Earth novels, spells are extremely complex word strings that must be memorized (ala D&D) and recited correctly. Reciting a spell incorrectly (whether from a written text or from memory) will change its effect, usually for the worse. This latter aspect of Vance's magic is not represented in the core D&D magic system (I think the closest that D&D ever came to modeling this aspect of Vance's magic was with the introduction of "Wild Magic" in AD&D 2e, and even that wasn't the same thing).
Another aspect of magic in The Dying Earth is that anybody can attmept to use it (i.e., if somebody can read a spell, they can attmept to memorize and/or recite it). This also isn't reflected in D&D by default -- the game has very specific rules about who can and cannot cast spells, which doesn't at all jibe with Vance's stories (Cugel, purely a rogue, manages to use magic in the stories, for example).
Finally, memorization of spells in The Dying Earth isn't a necessity -- the only time characters are seen doing it is when they don't want to be bothered with carrying around a big ass, iron-hinged, tome of knowldge with them because they'll be travelling or when they're using spells as concealed weapons (or attempting to, in Cugel's case).
Really, the only thing D&D magic has in common with Vance's magic as seen in The Dying Earth is the fact that it can be memorized. Well, and those shamelessly 'borrowed' spells (e.g., Prisimatic Spray) and magic items (e.g., "Ioun Stones"). As for Leiber's magic. . .
I beleve that the only place this shows up in D&D (overtly, anyhow) is via magic items -- the "Cloak of Invisibility" for example, first appeared by that same proper name in the Leiber short story Bazaar of the Bizarre in 1963. Tolkien? I'm 90% certain that specific spells (e.g., fireball) were inspired by Tolkien, though that's purely speculation on my part.
Overall, the D&D arcane magic system is much more original than many people give it credit for. D&D holy magic, on the other hand, is pretty obviously a pastiche of real life religious beliefs (e.g., power in exhange for prayer).