Joseph Fielding Smith said,

We have often heard of guardian angels attending us and many patriarchs have spoken of such protection. There are times no doubt when some unseen power directs us and leads us from harm. However, the true guardian angel given to every man who comes into the world is the Light of Truth or Spirit of Christ. The Holy Ghost is given to faithful members of the Church to guard and direct them; theirs is the privilege, through their faithfulness, to have such guidance and protection.

(President Joseph Fielding Smith, Doctrines of Salvation 1:54)