A split hardware transaction may split an atomic block of code to be executed using multiple hardware transactions, while logically taking effect as a single atomic transaction. A split hardware transaction may use software to combine the multiple hardware transactions into one logically atomic operation. In some embodiments, a split hardware transaction may allow execution of atomic blocks including non-hardware-transactionable (NHT) operations without resorting to exclusively software transactions. A split hardware transaction may maintain a thread-local buffer logs all memory accesses performed by the split hardware transaction. A split hardware transaction may use a hardware transaction to copy values read from shared memory locations into a local memory buffer. To execute a non-hardware-transactionable operation, the split hardware transaction may commit the active hardware transaction, execute the non-hardware-transactionable operation, and then initiate a new hardware transaction to execute the rest of the atomic block.