diff --git a/src/system/libroot/posix/glibc/arch/generic/s_signbitl.c b/src/system/libroot/posix/glibc/arch/generic/s_signbitl.c
new file mode 100644
index 0000000000..aa8dc8656f
--- /dev/null
+++ b/src/system/libroot/posix/glibc/arch/generic/s_signbitl.c
@@ -0,0 +1,32 @@
+/* Return nonzero value if number is negative.
+   Copyright (C) 1997 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <math.h>
+
+#include "math_private.h"
+
+int
+__signbitl (long double x)
+{
+  int32_t e;
+
+  GET_LDOUBLE_EXP (e, x);
+  return e & 0x8000;
+}
diff --git a/src/system/libroot/posix/glibc/arch/x86/Jamfile b/src/system/libroot/posix/glibc/arch/x86/Jamfile
index 33d05fce3e..2b91cb6b43 100644
--- a/src/system/libroot/posix/glibc/arch/x86/Jamfile
+++ b/src/system/libroot/posix/glibc/arch/x86/Jamfile
@@ -36,6 +36,7 @@ local genericSources =
 	s_isnan.c s_isnanf.c
 	s_ldexp.c s_ldexpf.c #s_ldexpl.c
 	s_modf.c s_modff.c # s_modfl.c
+	s_signbit.c s_signbitl.c
 	s_round.c s_roundf.c # s_roundl.c
 	s_signgam.c
 	s_tanh.c s_tanhf.c