diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
index 9df5f6ad..d9098584 100644
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -13,6 +13,7 @@ set(SOURCES
     src/ctype.cpp
     src/time.cpp
     src/init.cpp
+    src/setjmp.cpp
     src/sys/stat.cpp
     src/sys/mman.cpp
     src/sys/wait.cpp
@@ -22,6 +23,7 @@ if(${LUNA_ARCH} STREQUAL "x86_64")
     set(SOURCES
         ${SOURCES}
         src/arch/x86_64/syscall.S
+        src/arch/x86_64/setjmp.S
     )
 endif()
 
diff --git a/libc/include/bits/attrs.h b/libc/include/bits/attrs.h
index 90de54d0..c9fa83bd 100644
--- a/libc/include/bits/attrs.h
+++ b/libc/include/bits/attrs.h
@@ -3,7 +3,7 @@
 #ifndef _BITS_ATTRS_H
 #define _BITS_ATTRS_H
 
-#if !defined(_STDLIB_H) && !defined(_STRING_H) && !defined(_ASSERT_H)
+#if !defined(_STDLIB_H) && !defined(_STRING_H) && !defined(_ASSERT_H) && !defined(_SETJMP_H)
 #error "Never include bits/attrs.h directly; use one of the standard library headers."
 #endif
 
diff --git a/libc/include/bits/fixed-size-types.h b/libc/include/bits/fixed-size-types.h
index 2003b0e9..0b700841 100644
--- a/libc/include/bits/fixed-size-types.h
+++ b/libc/include/bits/fixed-size-types.h
@@ -3,7 +3,7 @@
 #ifndef _BITS_FIXED_SIZE_TYPES_H
 #define _BITS_FIXED_SIZE_TYPES_H
 
-#ifndef _SYS_TYPES_H
+#if !defined(_SYS_TYPES_H) && !defined(_BITS_SETJMP_TYPES_H)
 #error "Never include bits/fixed-size-types.h, use the standard <stdint.h> header instead."
 #endif
 
diff --git a/libc/include/bits/platform.h b/libc/include/bits/platform.h
new file mode 100644
index 00000000..31930401
--- /dev/null
+++ b/libc/include/bits/platform.h
@@ -0,0 +1,13 @@
+/* bits/platform.h: Platform defines. */
+
+#ifndef _BITS_PLATFORM_H
+#define _BITS_PLATFORM_H
+
+#if defined(__x86_64__)
+#define __libc_arch_x86_64
+#define __libc_arch_x86
+#else
+#define __libc_arch_unknown
+#endif
+
+#endif
diff --git a/libc/include/bits/setjmp-types.h b/libc/include/bits/setjmp-types.h
new file mode 100644
index 00000000..439f7a38
--- /dev/null
+++ b/libc/include/bits/setjmp-types.h
@@ -0,0 +1,20 @@
+/* bits/setjmp-types.h: Architecture-dependent definitions for jmp_buf/sigjmp_buf. */
+
+#ifndef _BITS_SETJMP_TYPES_H
+#define _BITS_SETJMP_TYPES_H
+
+#include <bits/fixed-size-types.h>
+#include <bits/platform.h>
+
+#ifndef _SETJMP_H
+#error "Never use bits/setjmp-types.h directly; include setjmp.h instead."
+#endif
+
+#ifdef __libc_arch_x86_64
+typedef __u64_t jmp_buf[8];
+typedef __u64_t sigjmp_buf[8];
+#else
+#error "Unsupported architecture."
+#endif
+
+#endif
diff --git a/libc/include/setjmp.h b/libc/include/setjmp.h
new file mode 100644
index 00000000..9538c94f
--- /dev/null
+++ b/libc/include/setjmp.h
@@ -0,0 +1,30 @@
+/* setjmp.h: nonlocal gotos. */
+
+#ifndef _SETJMP_H
+#define _SETJMP_H
+
+#include <bits/attrs.h>
+#include <bits/setjmp-types.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /* Saves the current execution state in env. */
+    int setjmp(jmp_buf env);
+
+    /* Right now, does the exact same thing as setjmp() (savesigs is ignored), since signals are not implemented. */
+    int sigsetjmp(sigjmp_buf env, int savesigs);
+
+    /* Restores the execution state saved in env by a setjmp() call. */
+    __noreturn void longjmp(jmp_buf env, int val);
+
+    /* Right now, does the exact same as longjmp(), since signals are not implemented. */
+    __noreturn void siglongjmp(sigjmp_buf env, int val);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/libc/src/arch/x86_64/setjmp.S b/libc/src/arch/x86_64/setjmp.S
new file mode 100644
index 00000000..ab37bfe5
--- /dev/null
+++ b/libc/src/arch/x86_64/setjmp.S
@@ -0,0 +1,36 @@
+.global _setjmp
+.global setjmp
+_setjmp:
+setjmp:
+    mov $0, %rsi
+    mov %rbx, (%rdi)
+    mov %r12, 0x8(%rdi)
+    mov %r13, 0x10(%rdi)
+    mov %r14, 0x18(%rdi)
+    mov %r15, 0x20(%rdi)
+    mov %rbp, 0x28(%rdi)
+    mov %rsp, 0x30(%rdi)
+    mov (%rsp), %rax
+    mov %rax, 0x38(%rdi)
+    xor %rax, %rax
+    ret
+
+.global _longjmp
+.global longjmp
+_longjmp:
+longjmp:
+    mov %rsi, %rax
+    cmp $0, %rax
+    jne .nonzero
+    mov $1, %rax
+.nonzero:
+    mov (%rdi), %rbx
+    mov 0x8(%rdi), %r12
+    mov 0x10(%rdi), %r13
+    mov 0x18(%rdi), %r14
+    mov 0x20(%rdi), %r15
+    mov 0x28(%rdi), %rbp
+    mov 0x30(%rdi), %rsp
+    mov 0x38(%rdi), %rcx
+    mov %rcx, (%rsp)
+    ret
diff --git a/libc/src/setjmp.cpp b/libc/src/setjmp.cpp
new file mode 100644
index 00000000..2d2bf673
--- /dev/null
+++ b/libc/src/setjmp.cpp
@@ -0,0 +1,14 @@
+#include <setjmp.h>
+
+extern "C"
+{
+    int sigsetjmp(sigjmp_buf env, int)
+    {
+        return setjmp(env);
+    }
+
+    __noreturn void siglongjmp(sigjmp_buf env, int val)
+    {
+        longjmp(env, val);
+    }
+}