The present invention relates to locked memory instructions, and more specifically to a system and method for the high performance execution of locked memory instructions in a system with distributed memory and a restrictive memory model. In accordance with an embodiment of the present invention, a method for executing locked-memory instructions includes decoding a locked-memory instruction, obtaining exclusive ownership of a cacheline to be used by a load-lock operation, setting a bit to indicate the load-lock operation's ownership of the cacheline, and activating a snoop checking process. The method also includes modifying a load data value and storing the modified load data value. The method further includes determining that the cacheline is still exclusively owned, storing the load data value, determining that the cacheline is unsnooped, merging the modified load data value with the load data value, and releasing the locked-memory instruction to be retired.