For processor cores, software-based self-test (SBST) is a promising complement to scan-based testing, especially for applications that demand high reliability. However, most prior SBST techniques only target stuck-at faults and thus fall short in detecting aging induced timing violations. In this paper, we propose an automatic test program generator for detection of transition delay faults (TDFs) in pipelined processors. The key technique is the conversion of scan-based launch-on-capture (LoC) TDF test patterns to instruction sequences, which are combined to form the self-test program. In the field, the processor under test can execute the test program on demand, in its functional mode, to detect TDFs. To facilitate the pattern-to-instruction conversion, a test program template is developed. Derived from the pipelined processor operation, the template helps systematically and efficiently set the flip-flop values specified in LoC test patterns. The proposed technique is validated on a MIPS32 processor and achieves 97.82% transition delay fault coverage.