Combine the garlic, basil and onion in a large bowl. Add the shrimp, olive oil and black pepper. Stir and let the shrimp marinate for 30 minutes.
Melt the butter and lemon juice in a saucepan over low heat. Add the butter and lemon juice to the shrimp mixture and toss.
Preheat a grill to 300 degrees F.
Thread the shrimp onto metal skewers. Arrange the skewers on the grill and grill until cooked through. Transfer the shrimp to a serving platter and serve.