LLVMpipe, which allows for running OpenGL on the CPU without the support of GPU and attempts to leverage LLVM for optimizations and taking advantage of multiple processing cores, simply isn't well-optimized yet. With the ARM Cortex-A15 being quite a nice upgrade over the Cortex-A9 ARM SoCs, I decided to build Mesa 9.1-devel Git with LLVM 3.1 on the Samsung Chromebook with its Exynos 5 Dual from Ubuntu 12.10.
While Gallium3D's LLVMpipe driver will run on ARM just as it has in the past, it's not too performant and optimized for this architecture. On x86, LLVMpipe really needs 64-bit support and multiple modern CPU cores (such as those boasting SSE4 and AVX) in order to deliver fairly low performance. On ARM, it just doesn't cut it yet without any ARM-specific optimizations. A modern ARM SoC is fast enough to get a compositing window manager running in software, but not really anything else that's useful.
Not All Linux Users Want To Toke On LLVMpipe.