diff --git a/sys/libkern/strlen.c b/sys/libkern/strlen.c
--- a/sys/libkern/strlen.c
+++ b/sys/libkern/strlen.c
@@ -26,9 +26,19 @@
  */
 
 #include <sys/cdefs.h>
+#include <sys/asan.h>
+#include <sys/csan.h>
 #include <sys/libkern.h>
 #include <sys/limits.h>
+#include <sys/msan.h>
 
+#if defined(KASAN) || defined(KCSAN) || defined(KMSAN)
+size_t
+(strlen)(const char *str)
+{
+	return SAN_INTERCEPTOR(strlen)(str);
+}
+#else /* KASAN || KCSAN || KMSAN */
 /*
  * Portable strlen() for 32-bit and 64-bit systems.
  *
@@ -119,3 +129,4 @@
 	/* NOTREACHED */
 	return (0);
 }
+#endif /* KASAN || KCSAN || KMSAN */