Index: devel/sdl20/Makefile
===================================================================
--- devel/sdl20/Makefile	(revision 387283)
+++ devel/sdl20/Makefile	(working copy)
@@ -189,5 +189,8 @@ CONFIGURE_ARGS+=	--disable-video-x11 \
 post-patch:
 	 @${REINPLACE_CMD} -e '/ CheckInputEvents$$/d' \
 		-e 's/-liconv/${ICONV_LIB}/g' ${WRKSRC}/configure
+# Clang does not provide _m_prefetch
+	@${REINPLACE_CMD} 's/_m_prefetch/__builtin_prefetch/' \
+		${WRKSRC}/configure ${WRKSRC}/src/video/SDL_blit_A.c
 
 .include <bsd.port.mk>