diff --git a/share/mk/doc.project.mk b/share/mk/doc.project.mk
index 244195bcbc..3d293f5a06 100644
--- a/share/mk/doc.project.mk
+++ b/share/mk/doc.project.mk
@@ -104,3 +104,9 @@ DOC_LOCAL_MK=	${DOC_PREFIX}/${LANGCODE}/share/mk/doc.local.mk
 
 # Subdirectory glue.
 .include "doc.subdir.mk"
+
+# parallel build for target "all"
+NCPU?= 8
+p-all:
+	make -V SUBDIR | sed -E 's/[ ]+$$//' | tr " " "\n" | sed -E 's/^/make -C /' | tr '\n' '\0' | xargs -0 -n1 -P${NCPU} /bin/sh -c
+