This paper presents a new approach to fault-tolerant control (FTC) based on control performance monitoring and real-time plant data without explicit fault detection and isolation algorithms. The approach sets forth the theory of unfalsified control to achieve a real-time reconfiguration of control laws which are consistent with the performance objectives for a class of system faults. The obtained FTC scheme may be viewed as an alternative or a complement to classical FTC structures based on explicit fault detectors and it provides a precise and direct characterization of suitable real-time controllers for fault accommodation.