$ icc -V Intel(R) C Intel(R) 64 Compiler XE for applications running on Intel(R) 64, Version 188.8.131.52 Build 20131008 Copyright (C) 1985-2013 Intel Corporation. All rights reserved. Although not documented icc accepts both -std=c11 and -std=gnu11, however it doesn't behave as C11 compiler, not even C99. It seems it would fall back to the default (as though I didn't specify -std). This is highly annoying in automatic environments (such as autoconf) where C11 compilers are preferred to C99 compilers, and in particular might fail for C99 code bases.
For more complete information about compiler optimizations, see our Optimization Notice.