U.S. law allows you to bring an unlimited amount of wine into the country when you are returning from a vacation abroad.
The TSA (Transportation Security Administration) limit on bringing alcohol into the country is divided into two categories: alcoholic beverages that contain between 24% and 70% alcohol, and alcoholic beverages that contain less than 24% alcohol. In the first case, you are limited to bringing in 5 liters per adult. Wine belongs in the second group since wine contains less than 24% alcohol. For the second group (wine), the amount an adult can bring in is unlimited. Of course, the airline carrier will have a weight limit, and you will have to abide by that. It helps to know that most bottles of wine are about 3 pounds. And in both cases above, bottles of alcohol must go in your checked (not carry on) luggage.