I would pronounce is "MAY-buh-leen." I love the name
Mabel, but
Maybelline will always be a cut-rate cosmetic company or a campy rock and roll song (by
Chuck Berry.)
You asked how it would be pronounced in English. Are you French?
German? Spanish? Other? (I'm from the U.S., so maybe someone from the U.K. would have a different take on this name in English.)