diff --git a/lib/bit.h b/lib/bit.h
new file mode 100644
index 00000000..24692557
--- /dev/null
+++ b/lib/bit.h
@@ -0,0 +1,41 @@
+/*
+ * SPDX-FileCopyrightText:  Alejandro Colomar <alx@kernel.org>
+ *
+ * SPDX-License-Identifier:  BSD-3-Clause
+ */
+
+
+#ifndef SHADOW_INCLUDE_LIB_BIT_H_
+#define SHADOW_INCLUDE_LIB_BIT_H_
+
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <limits.h>
+
+
+inline unsigned long bit_ceil_wrapul(unsigned long x);
+inline int leading_zerosul(unsigned long x);
+
+
+/* stdc_bit_ceilul(3), but wrap instead of having Undefined Behavior */
+inline unsigned long
+bit_ceil_wrapul(unsigned long x)
+{
+	if (x == 0)
+		return 0;
+
+	return 1 + (ULONG_MAX >> leading_zerosul(x));
+}
+
+/* stdc_leading_zerosul(3) */
+inline int
+leading_zerosul(unsigned long x)
+{
+	return (x == 0) ? ULONG_WIDTH : __builtin_clz(x);
+}
+
+
+#endif  // include guard
diff --git a/libmisc/Makefile.am b/libmisc/Makefile.am
index b4ca708d..ab363f54 100644
--- a/libmisc/Makefile.am
+++ b/libmisc/Makefile.am
@@ -12,6 +12,7 @@ libmisc_la_SOURCES = \
 	agetpass.c \
 	audit_help.c \
 	basename.c \
+	bit.c \
 	chkname.c \
 	chkname.h \
 	chowndir.c \
diff --git a/libmisc/bit.c b/libmisc/bit.c
new file mode 100644
index 00000000..39efd568
--- /dev/null
+++ b/libmisc/bit.c
@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText:  Alejandro Colomar <alx@kernel.org>
+ *
+ * SPDX-License-Identifier:  BSD-3-Clause
+ */
+
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include "bit.h"
+
+#include <limits.h>
+
+
+extern inline unsigned long bit_ceil_wrapul(unsigned long x);
+extern inline int leading_zerosul(unsigned long x);