Nothing can really replace the flavor and aroma of fresh garlic. Do you have trouble finding fresh garlic? Sometimes grocery stores will sell fresh garlic that has been peeled, which is very convenient without losing the freshness of the garlic.
To peel garlic quickly, place a heavy chef's knife over the bulb on a cutting board, and whack the knife with the palm of your hand so the garlic skin splits. Then grab the garlic by the top, stem end (just the tip), hold the bulb above the board, and gently tap the body of the garlic with the wide side of the knife. The bulb will fall right out of the skin. Sometime the bulb is broken, but it will still release from the skin easily.