diff --git a/src/x86/siglongjmp.S b/src/x86/siglongjmp.S
index c43c9843..51bbb505 100644
--- a/src/x86/siglongjmp.S
+++ b/src/x86/siglongjmp.S
@@ -1,10 +1,68 @@
-	/* Dummy implementation for now.  Libunwind-based setjmp/longjmp
-	   can't work on x86 until we take advantage of DWARF2 unwind info.  */
+/* libunwind - a platform-independent unwind library
+   Copyright (C) 2004 Hewlett-Packard Co
+	Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
+
+This file is part of libunwind.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
 
 	.globl _UI_siglongjmp_cont
-	.globl _UI_longjmp_cont
 
+#define SIG_SETMASK 2
+
+	/* Stack layout at this point:
+
+		+------------+ <- original $esp (at time of setjmp() call)
+		| sigmask[1] |
+		+------------+
+		| sigmask[0] |
+		+------------+
+	 */
+
+	.type _UI_siglongjmp_cont, @function
 _UI_siglongjmp_cont:
-_UI_longjmp_cont:
-#warning fix me
-	ret
+	.cfi_startproc
+	.cfi_register 8, 0	/* IP saved in EAX */
+	.cfi_def_cfa_offset 8
+	mov %esp, %ecx		/* pass address of signal mask in 3rd sc arg */
+	push %eax		/* save target IP */
+	.cfi_adjust_cfa_offset 4
+	.cfi_offset 8, -12
+	push %edx		/* save return value */
+	.cfi_adjust_cfa_offset 4
+	push %ebx		/* save %ebx (preserved) */
+	.cfi_adjust_cfa_offset 4
+	.cfi_offset 3, -20
+	mov $SIG_SETMASK, %ebx	/* 1st syscall arg (how) */
+	xor %edx, %edx		/* pass NULL as 3rd syscall arg (old maskp) */
+	int $0x80
+	pop %ebx		/* restore %ebx */
+	.cfi_adjust_cfa_offset -4
+	.cfi_restore 3
+	pop %eax		/* fetch return value */
+	.cfi_adjust_cfa_offset -4
+	pop %edx		/* pop target IP */
+	.cfi_adjust_cfa_offset -4
+	.cfi_register 8, 2	/* saved IP is now n EDX */
+	lea 8(%esp), %esp	/* pop sigmask */
+	.cfi_adjust_cfa_offset -4
+	jmp *%edx
+	.cfi_endproc
+	.size _UI_siglongjmp_cont, .-_UI_siglongjmp_cont