The prayer Alma used:
Helam, I baptize thee, having authority from the Almighty God, as a testimony that ye have entered into a covenant to serve him until you are dead as to the mortal body; and may the Spirit of the Lord be poured out upon you; and may he grant unto you eternal life, through the redemption of Christ, whom he has prepared from the foundation of the world.
The prayer we use now:
John Smith, having been commissioned of Jesus Christ, I baptize you in the name of the Father, and of the Son, and of the Holy Ghost.