diff --git a/usr.sbin/config/mkmakefile.cc b/usr.sbin/config/mkmakefile.cc
--- a/usr.sbin/config/mkmakefile.cc
+++ b/usr.sbin/config/mkmakefile.cc
@@ -384,13 +384,25 @@
 	struct file_list *tp;
 	struct device *dp;
 	struct opt *op;
+	struct includepath *ipath;
 	configword wd;
-	char *rfile, *compilewith, *depends, *clean, *warning;
+	char *rfile, *compilewith, *depends, *clean, *fnamebuf, *warning;
 	const char *objprefix;
 	int compile, match, nreqs, std, filetype, negate,
 	    imp_rule, no_ctfconvert, no_obj, before_depend, nowerror;
 
 	fp = fopen(fname, "r");
+	if (fp == NULL) {
+		SLIST_FOREACH(ipath, &includepath, path_next) {
+			asprintf(&fnamebuf, "%s/%s", ipath->path, fname);
+			if (fnamebuf != NULL) {
+				fp = fopen(fnamebuf, "r");
+				if (fp != NULL)
+					break;
+				free(fnamebuf);
+			}
+		}
+	}
 	if (fp == NULL)
 		err(1, "%s", fname);
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