Index: configure.in.in
===================================================================
--- configure.in.in	(revision 16851)
+++ configure.in.in	(working copy)
@@ -141,7 +141,14 @@
   dnl Fallback to a generic FAM check
   AC_CHECK_HEADERS([fam.h],
   [
-    AC_CHECK_LIB([fam], [FAMOpen], [have_libfam="yes" LIBFAM_LIBS="-lfam"])
+    AC_CHECK_LIB([fam], [FAMOpen], [have_libfam="yes" LIBFAM_LIBS="-lfam"],
+    [
+      dnl IRIX requires -lC to detect -lfam
+      save_LIBS="$LIBS"
+      LIBS="$LIBS -lC"
+      AC_CHECK_LIB(fam, [FAMOpen], [have_libfam="yes" LIBFAM_LIBS="-lC -lfam"])
+      LIBS="$save_LIBS"
+    ])
   ])
 ])
 if test x"$have_libfam" = x"yes"; then