CONFIG_CPU_HAS_LLSC is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_CPU_HAS_LLSC (not configurable)

configname: CONFIG_CPU_HAS_LLSC

Linux/MIPS Kernel Configuration
└─>Kernel type
└─>CPU_HAS_LLSC
In linux kernel since version 2.6.12