--- ../mkspecs/common/clang-unix.conf.orig	2013-12-05 22:57:53.135156000 +0000
+++ ../mkspecs/common/clang-unix.conf	2013-12-05 23:09:36.960149415 +0000
@@ -0,0 +1,15 @@
+#
+# Qmake configuration for the Clang compiler on *nix-systems
+#
+# Before making changes to this file, please read the comment in
+# gcc-base.conf, to make sure the change goes in the right place.
+#
+# To verify that your change has the desired effect on the final configuration
+# you can use the manual test in tests/manual/mkspecs.
+#
+
+include(gcc-base-unix.conf)
+include(clang.conf)
+
+QMAKE_LFLAGS_RELEASE += -Wl,-O1
+QMAKE_LFLAGS_NOUNDEF += -Wl,--no-undefined