Libtool checks only for libraries linked as -l* when trying to
find internal compiler libraries. Clang, however uses the absolute
path to link its internal libraries e.g. compiler_rt. This patch
handles clang's statically linked libraries when finding internal
compiler libraries.
https://crbug.com/749263
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=27866

--- a/m4/libtool.m4
+++ b/m4/libtool.m4
@@ -7531,7 +7544,7 @@
   for p in `eval "$output_verbose_link_cmd"`; do
     case $prev$p in

-    -L* | -R* | -l*)
+    -L* | -R* | -l* | */libclang_rt.*.a)
        # Some compilers place space between "-{L,R}" and the path.
        # Remove the space.
        if test x-L = "$p" ||