diff --git a/lib/libc/gen/Makefile.inc b/lib/libc/gen/Makefile.inc
index 4e30df5aaabc..5e459fc67ffe 100644
--- a/lib/libc/gen/Makefile.inc
+++ b/lib/libc/gen/Makefile.inc
@@ -3,6 +3,7 @@
 
 # machine-independent gen sources
 .PATH: ${LIBC_SRCTOP}/${LIBC_ARCH}/gen ${LIBC_SRCTOP}/gen
+.PATH: ${SRCTOP}/sys/libkern
 
 CONFS=	shells
 
diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
index 863a1135f5a6..7a7154dae6d3 100644
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -1668,6 +1668,8 @@ MLINKS+=psignal.9 gsignal.9 \
 	psignal.9 tdsignal.9
 MLINKS+=random.9 arc4rand.9 \
 	random.9 arc4random.9 \
+	random.9 arc4random_buf.9 \
+	random.9 arc4random_uniform.9 \
 	random.9 is_random_seeded.9 \
 	random.9 read_random.9 \
 	random.9 read_random_uio.9 \
diff --git a/share/man/man9/random.9 b/share/man/man9/random.9
index 97218dcab39c..1537e28dd356 100644
--- a/share/man/man9/random.9
+++ b/share/man/man9/random.9
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\" "
-.Dd April 16, 2019
+.Dd April 19, 2019
 .Dt RANDOM 9
 .Os
 .Sh NAME
@@ -45,6 +45,8 @@
 .Fn arc4random "void"
 .Ft void
 .Fn arc4random_buf "void *ptr" "size_t len"
+.Ft uint32_t
+.Fn arc4random_uniform "uint32_t upper_bound"
 .Ft void
 .Fn arc4rand "void *ptr" "u_int length" "int reseed"
 .Pp
@@ -80,6 +82,15 @@ with
 .Fa len
 bytes of random data.
 .Pp
+.Fn arc4random_uniform
+will return a single 32-bit value, uniformly distributed but less than
+.Fa upper_bound .
+This is recommended over constructions like
+.Dq Li arc4random() % upper_bound
+as it avoids "modulo bias" when the upper bound is not a power of two.
+In the worst case, this function may consume multiple iterations
+to ensure uniformity.
+.Pp
 The
 .Fn arc4rand
 CSPRNG
diff --git a/sys/conf/files b/sys/conf/files
index 90057c557cb5..9f2f00382c19 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -3985,6 +3985,7 @@ kgssapi/gsstest.c		optional kgssapi_debug
 # the file should be moved to conf/files.<arch> from here.
 #
 libkern/arc4random.c		standard
+libkern/arc4random_uniform.c	standard
 crypto/chacha20/chacha.c	standard
 libkern/asprintf.c		standard
 libkern/bcd.c			standard
diff --git a/lib/libc/gen/arc4random_uniform.c b/sys/libkern/arc4random_uniform.c
similarity index 97%
rename from lib/libc/gen/arc4random_uniform.c
rename to sys/libkern/arc4random_uniform.c
index 0136c66e3289..26f91e6532f9 100644
--- a/lib/libc/gen/arc4random_uniform.c
+++ b/sys/libkern/arc4random_uniform.c
@@ -19,7 +19,11 @@
  */
 
 #include <sys/types.h>
+#ifdef _KERNEL
+#include <sys/libkern.h>
+#else
 #include <stdlib.h>
+#endif
 
 /*
  * Calculate a uniformly distributed random number less than upper_bound
diff --git a/sys/sys/libkern.h b/sys/sys/libkern.h
index 123f6eeda3f3..1d7dcc369f0f 100644
--- a/sys/sys/libkern.h
+++ b/sys/sys/libkern.h
@@ -128,6 +128,7 @@ struct malloc_type;
 uint32_t arc4random(void);
 void	 arc4random_buf(void *, size_t);
 void	 arc4rand(void *, u_int, int);
+uint32_t arc4random_uniform(uint32_t);
 int	 timingsafe_bcmp(const void *, const void *, size_t);
 void	*bsearch(const void *, const void *, size_t,
 	    size_t, int (*)(const void *, const void *));