1. A patient-specific surgical guide for intra-operatively creating a patient-specific augment adapted for mounting a prosthetic implant on a bone of a patient, the patient-specific surgical guide comprising: a base fixture including a mounting surface having a bone retaining portion thereon within which an unformed augment blank is receivable; and a patient-specific cutting guide engaged to the base fixture, the patient-specific cutting guide having one or more cutting guide surfaces which are customized in position and orientation for said patient and configured to guide a surgical implement to re-shape the unformed augment blank to create said patient-specific augment, wherein the patient-specific augment has a size and shape corresponding to a portion of the bone adapted to receive the prosthetic implant such that the patient-specific augment will conform to said portion of the bone for abutment therewith; wherein the patient-specific cutting guide is mounted to the base fixture for displacement between an open inoperable position and a closed bone cutting position, the bone retaining portion of the base fixture being accessible to receive the unformed augment blank therein when the patient-specific cutting guide is disposed in the open inoperable position, and the cutting guide surfaces of the patient-specific cutting guide being disposed in position to allow said re-shaping of the unformed augment blank when the patient-specific cutting guide is disposed in said closed bone cutting position.