diff --git a/configure b/configure
index a2728969..43598825 100755
--- a/configure
+++ b/configure
@@ -494,6 +494,13 @@ fnmatch '-march=*|*\ -march=*' "$CC $CFLAGS" || tryldflag CFLAGS_AUTO -march=i48
 fnmatch '-mtune=*|*\ -mtune=*' "$CC $CFLAGS" || tryldflag CFLAGS_AUTO -mtune=generic
 fi
 
+#
+# GCC defines -w as overriding any -W options, regardless of order, but
+# clang has a bunch of annoying warnings enabled by default and needs -w
+# to start from a clean slate. So use -w if building with clang.
+#
+test "$cc_family" = clang && tryflag CFLAGS_AUTO -w
+
 #
 # Even with -std=c99, gcc accepts some constructs which are constraint
 # violations. We want to treat these as errors regardless of whether