diff --git a/include/math.h b/include/math.h
index 81778e429..264fe0f73 100644
--- a/include/math.h
+++ b/include/math.h
@@ -34,6 +34,10 @@ _PROTOTYPE( double log10, (double _x)					);
 _PROTOTYPE( double modf,  (double _x, double *_iptr)			);
 _PROTOTYPE( double pow,   (double _x, double _y)			);
 _PROTOTYPE( double rint,  (double _x)					);
+_PROTOTYPE( double scalbn, (double _x, int _exp)			);
+_PROTOTYPE( float scalbnf, (float _x, int _exp)				);
+_PROTOTYPE( double scalbln, (double _x, long _exp)			);
+_PROTOTYPE( float scalblnf, (float _x, long _exp)			);
 _PROTOTYPE( double sin,   (double _x)					);
 _PROTOTYPE( double sinh,  (double _x)					);
 _PROTOTYPE( double sqrt,  (double _x)					);
diff --git a/lib/math/Makefile.in b/lib/math/Makefile.in
index 434ca242e..3d949b73f 100644
--- a/lib/math/Makefile.in
+++ b/lib/math/Makefile.in
@@ -19,6 +19,7 @@ libc_FILES=" \
 	log10.c \
 	pow.c \
 	s_rint.c \
+	scalbn.c \
 	sin.c \
 	sinh.c \
 	sqrt.c \
diff --git a/lib/math/scalbn.c b/lib/math/scalbn.c
new file mode 100644
index 000000000..311c40e01
--- /dev/null
+++ b/lib/math/scalbn.c
@@ -0,0 +1,22 @@
+#include <math.h>
+
+double scalbln(double x, long n)
+{
+	return ldexp(x, n);
+}
+
+float scalblnf(float x, long n)
+{
+	return ldexp(x, n);
+}
+
+double scalbn(double x, int n)
+{
+	return ldexp(x, n);
+}
+
+float scalbnf(float x, int n)
+{
+	return ldexp(x, n);
+}
+
diff --git a/man/man3/ldexp.3 b/man/man3/ldexp.3
new file mode 100644
index 000000000..87792d487
--- /dev/null
+++ b/man/man3/ldexp.3
@@ -0,0 +1,19 @@
+.TH LDEXP 3 "January 7, 2009"
+.UC 4
+.SH NAME
+ldexp, scalbn, scalbnf, scalbln, scalblnf \- compute absolute value
+.SH SYNOPSIS
+.nf
+.ft B
+#include <math.h>
+
+double ldexp(double \fIx\fP, int \fIn\fP);
+double scalbn(double \fIx\fP, int \fIn\fP);
+float scalbnf(float \fIx\fP, int \fIn\fP);
+double scalbln(double \fIx\fP, long \fIn\fP);
+float scalblnf(float \fIx\fP, long \fIn\fP);
+.fi
+.SH DESCRIPTION
+These functions all compute \fIx\fP * 2^\fIn\fP.
+.SH "RETURN VALUE
+These functions all return \fIx\fP * 2^\fIn\fP.