Index: head/contrib/compiler-rt/lib/builtins/multc3.c
===================================================================
--- head/contrib/compiler-rt/lib/builtins/multc3.c
+++ head/contrib/compiler-rt/lib/builtins/multc3.c
@@ -0,0 +1,73 @@
+/* ===-- multc3.c - Implement __multc3 -------------------------------------===
+ *
+ *                     The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ *
+ * This file implements __multc3 for the compiler_rt library.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#include "int_lib.h"
+#include "int_math.h"
+
+/* Returns: the product of a + ib and c + id */
+
+COMPILER_RT_ABI long double _Complex
+__multc3(long double __a, long double __b, long double __c, long double __d)
+{
+    long double __ac = __a * __c;
+    long double __bd = __b * __d;
+    long double __ad = __a * __d;
+    long double __bc = __b * __c;
+    long double _Complex z;
+    __real__ z = __ac - __bd;
+    __imag__ z = __ad + __bc;
+    if (crt_isnan(__real__ z) && crt_isnan(__imag__ z))
+    {
+        int __recalc = 0;
+        if (crt_isinf(__a) || crt_isinf(__b))
+        {
+            __a = crt_copysignl(crt_isinf(__a) ? 1 : 0, __a);
+            __b = crt_copysignl(crt_isinf(__b) ? 1 : 0, __b);
+            if (crt_isnan(__c))
+                __c = crt_copysignl(0, __c);
+            if (crt_isnan(__d))
+                __d = crt_copysignl(0, __d);
+            __recalc = 1;
+        }
+        if (crt_isinf(__c) || crt_isinf(__d))
+        {
+            __c = crt_copysignl(crt_isinf(__c) ? 1 : 0, __c);
+            __d = crt_copysignl(crt_isinf(__d) ? 1 : 0, __d);
+            if (crt_isnan(__a))
+                __a = crt_copysignl(0, __a);
+            if (crt_isnan(__b))
+                __b = crt_copysignl(0, __b);
+            __recalc = 1;
+        }
+        if (!__recalc && (crt_isinf(__ac) || crt_isinf(__bd) ||
+                          crt_isinf(__ad) || crt_isinf(__bc)))
+        {
+            if (crt_isnan(__a))
+                __a = crt_copysignl(0, __a);
+            if (crt_isnan(__b))
+                __b = crt_copysignl(0, __b);
+            if (crt_isnan(__c))
+                __c = crt_copysignl(0, __c);
+            if (crt_isnan(__d))
+                __d = crt_copysignl(0, __d);
+            __recalc = 1;
+        }
+        if (__recalc)
+        {
+            __real__ z = CRT_INFINITY * (__a * __c - __b * __d);
+            __imag__ z = CRT_INFINITY * (__a * __d + __b * __c);
+        }
+    }
+    return z;
+}
Index: head/lib/libcompiler_rt/Makefile
===================================================================
--- head/lib/libcompiler_rt/Makefile
+++ head/lib/libcompiler_rt/Makefile
@@ -108,6 +108,7 @@
 	mulvdi3 \
 	mulvsi3 \
 	mulvti3 \
+	multc3 \
 	mulxc3 \
 	negdf2 \
 	negdi2 \