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

CONFIG_WEAK_REORDERING_BEYOND_LLSC (not configurable)

configname: CONFIG_WEAK_REORDERING_BEYOND_LLSC

Linux Kernel Configuration
└─>CPU selection
└─>WEAK_REORDERING_BEYOND_LLSC
In linux kernel since version 2.6.23 (release Date: 2007-10-09)  
is depended by
CONFIG_CPU_LOONGSON64