--- a/configure.in
+++ b/configure.in
@@ -6717,16 +6717,21 @@ dnl =
 dnl ========================================================
 MOZ_ARG_HEADER(Static build options)
 
 MOZ_ARG_ENABLE_BOOL(static,
 [  --enable-static         Enable building of internal static libs],
     BUILD_STATIC_LIBS=1,
     BUILD_STATIC_LIBS=)
 
+dnl Disable libxul in debug builds.
+if test -n "$MOZ_DEBUG"; then
+   MOZ_ENABLE_LIBXUL=
+fi
+
 MOZ_ARG_ENABLE_BOOL(libxul,
 [  --enable-libxul         Enable building of libxul],
     MOZ_ENABLE_LIBXUL=1,
     MOZ_ENABLE_LIBXUL=)
 
 if test -n "$MOZ_ENABLE_LIBXUL" -a -n "$BUILD_STATIC_LIBS"; then
 	AC_MSG_ERROR([--enable-libxul is not compatible with --enable-static])
 fi