there should be no warnings; on older and on non-GNU systems the
generated warnings may still be useful.
-Use --enable-link-time-optimization to enable link-time optimizer, which
-is available in GNU compiler since version 4.5.0. If your compiler is not
-GNU or older than version 4.5.0, this option does nothing. If `configure'
-can determine number of online CPUS on your system, final link-time
-optimization and code generation is executed in parallel using one job
-per each available online CPU.
+Use --enable-link-time-optimization to enable link-time optimizer. If
+you're using GNU compiler, this feature is supported since version 4.5.0.
+If `configure' can determine number of online CPUS on your system, final
+link-time optimization and code generation is executed in parallel using
+one job per each available online CPU.
+
+This option is also supported for clang. You should have GNU binutils
+with `gold' linker and plugin support, and clang with LLVMgold.so plugin.
+Read http://llvm.org/docs/GoldPlugin.html for details. Also note that
+this feature is still experimental, so prepare to build binutils and
+clang from the corresponding source code repositories.
The `--prefix=PREFIXDIR' option specifies where the installation process
should put emacs and its data files. This defaults to `/usr/local'.