The correct sentence should be: "If he comes, I shall go with him."
Explanation: The structure "If he will come" is incorrect in this context. In the "if" clause, we use the present tense ("comes") to refer to future events in conditional sentences.
Incorrect Sentence: If he will come, I shall go with him.
Corrected Sentence: If he comes, I shall go with him.
\boxed{\text{If he comes, I shall go with him.}}