diff --git a/libm/amd64/fenv.c b/libm/amd64/fenv.c
new file mode 100644
index 0000000..2b43678
--- /dev/null
+++ b/libm/amd64/fenv.c
@@ -0,0 +1,148 @@
+/*-
+ * Copyright (c) 2004-2005 David Schultz <das@FreeBSD.ORG>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD: src/lib/msun/amd64/fenv.c,v 1.3 2005/03/16 19:03:45 das Exp $
+ */
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+#include <machine/fpu.h>
+#include <fenv.h>
+
+const fenv_t __fe_dfl_env = {
+	{ 0xffff0000 | __INITIAL_FPUCW__,
+	  0xffff0000,
+	  0xffffffff,
+	  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff }
+	},
+	__INITIAL_MXCSR__
+};
+
+int
+fesetexceptflag(const fexcept_t *flagp, int excepts)
+{
+	fenv_t env;
+
+	__fnstenv(&env.__x87);
+	env.__x87.__status &= ~excepts;
+	env.__x87.__status |= *flagp & excepts;
+	__fldenv(env.__x87);
+
+	__stmxcsr(&env.__mxcsr);
+	env.__mxcsr &= ~excepts;
+	env.__mxcsr |= *flagp & excepts;
+	__ldmxcsr(env.__mxcsr);
+
+	return (0);
+}
+
+int
+feraiseexcept(int excepts)
+{
+	fexcept_t ex = excepts;
+
+	fesetexceptflag(&ex, excepts);
+	__fwait();
+	return (0);
+}
+
+int
+fegetenv(fenv_t *envp)
+{
+	int control;
+
+	/*
+	 * fnstenv masks all exceptions, so we need to save and
+	 * restore the control word to avoid this side effect.
+	 */
+	__fnstcw(&control);
+	__fnstenv(&envp->__x87);
+	__stmxcsr(&envp->__mxcsr);
+	__fldcw(control);
+	return (0);
+}
+
+int
+feholdexcept(fenv_t *envp)
+{
+	int mxcsr;
+
+	__stmxcsr(&mxcsr);
+	__fnstenv(&envp->__x87);
+	__fnclex();
+	envp->__mxcsr = mxcsr;
+	mxcsr &= ~FE_ALL_EXCEPT;
+	mxcsr |= FE_ALL_EXCEPT << _SSE_EMASK_SHIFT;
+	__ldmxcsr(mxcsr);
+	return (0);
+}
+
+int
+feupdateenv(const fenv_t *envp)
+{
+	int mxcsr, status;
+
+	__fnstsw(&status);
+	__stmxcsr(&mxcsr);
+	fesetenv(envp);
+	feraiseexcept((mxcsr | status) & FE_ALL_EXCEPT);
+	return (0);
+}
+
+int
+__feenableexcept(int mask)
+{
+	int mxcsr, control, omask;
+
+	mask &= FE_ALL_EXCEPT;
+	__fnstcw(&control);
+	__stmxcsr(&mxcsr);
+	omask = (control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
+	control &= ~mask;
+	__fldcw(control);
+	mxcsr &= ~(mask << _SSE_EMASK_SHIFT);
+	__ldmxcsr(mxcsr);
+	return (~omask);
+}
+
+int
+__fedisableexcept(int mask)
+{
+	int mxcsr, control, omask;
+
+	mask &= FE_ALL_EXCEPT;
+	__fnstcw(&control);
+	__stmxcsr(&mxcsr);
+	omask = (control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
+	control |= mask;
+	__fldcw(control);
+	mxcsr |= mask << _SSE_EMASK_SHIFT;
+	__ldmxcsr(mxcsr);
+	return (~omask);
+}
+
+__weak_reference(__feenableexcept, feenableexcept);
+__weak_reference(__fedisableexcept, fedisableexcept);