diff --git a/kernel/include/sortix/exit.h b/kernel/include/sortix/exit.h
new file mode 100644
index 00000000..85ca5535
--- /dev/null
+++ b/kernel/include/sortix/exit.h
@@ -0,0 +1,55 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2013, 2014.
+
+    This file is part of Sortix.
+
+    Sortix is free software: you can redistribute it and/or modify it under the
+    terms of the GNU General Public License as published by the Free Software
+    Foundation, either version 3 of the License, or (at your option) any later
+    version.
+
+    Sortix 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 General Public License for more
+    details.
+
+    You should have received a copy of the GNU General Public License along with
+    Sortix. If not, see <http://www.gnu.org/licenses/>.
+
+    sortix/exit.h
+    Flags and constants related to process and thread exiting.
+
+*******************************************************************************/
+
+#ifndef INCLUDE_SORTIX_EXIT_H
+#define INCLUDE_SORTIX_EXIT_H
+
+#include <sys/cdefs.h>
+
+#include <sys/__/types.h>
+
+__BEGIN_DECLS
+
+#ifndef __size_t_defined
+#define __size_t_defined
+#define __need_size_t
+#include <stddef.h>
+#endif
+
+struct exit_thread
+{
+	void* unmap_from;
+	size_t unmap_size;
+	void* zero_from;
+	size_t zero_size;
+	unsigned long reserved[4];
+};
+
+#define EXIT_THREAD_ONLY_IF_OTHERS (1<<0)
+#define EXIT_THREAD_UNMAP (1<<1)
+#define EXIT_THREAD_ZERO (1<<2)
+
+__END_DECLS
+
+#endif
diff --git a/kernel/include/sortix/syscallnum.h b/kernel/include/sortix/syscallnum.h
index c182a1cc..9fdcd86e 100644
--- a/kernel/include/sortix/syscallnum.h
+++ b/kernel/include/sortix/syscallnum.h
@@ -153,6 +153,7 @@
 #define SYSCALL_RDMSR 129
 #define SYSCALL_WRMSR 130
 #define SYSCALL_SCHED_YIELD 131
-#define SYSCALL_MAX_NUM 132 /* index of highest constant + 1 */
+#define SYSCALL_EXIT_THREAD 132
+#define SYSCALL_MAX_NUM 133 /* index of highest constant + 1 */
 
 #endif
diff --git a/kernel/thread.cpp b/kernel/thread.cpp
index a1abce0b..174cea62 100644
--- a/kernel/thread.cpp
+++ b/kernel/thread.cpp
@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
+    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2014.
 
     This file is part of Sortix.
 
@@ -26,9 +26,11 @@
 #include <errno.h>
 #include <string.h>
 
+#include <sortix/exit.h>
 #include <sortix/mman.h>
 #include <sortix/signal.h>
 
+#include <sortix/kernel/copy.h>
 #include <sortix/kernel/interrupt.h>
 #include <sortix/kernel/kernel.h>
 #include <sortix/kernel/kthread.h>
@@ -279,6 +281,61 @@ bool Thread::DeliverSignal(int signum)
 	return true;
 }
 
+static int sys_exit_thread(int status,
+                           int flags,
+                           const struct exit_thread* user_extended)
+{
+	if ( flags & ~(EXIT_THREAD_ONLY_IF_OTHERS |
+	               EXIT_THREAD_UNMAP |
+	               EXIT_THREAD_ZERO) )
+		return errno = EINVAL, -1;
+
+	Thread* thread = CurrentThread();
+	Process* process = CurrentProcess();
+
+	struct exit_thread extended;
+	if ( !user_extended )
+		memset(&extended, 0, sizeof(extended));
+	else if ( !CopyFromUser(&extended, user_extended, sizeof(extended)) )
+		return -1;
+
+	extended.unmap_size = Page::AlignUp(extended.unmap_size);
+
+	kthread_mutex_lock(&thread->process->threadlock);
+	bool is_others = false;
+	for ( Thread* iter = thread->process->firstthread;
+	      !is_others && iter;
+	     iter = iter->nextsibling )
+	{
+		if ( iter == thread )
+			continue;
+		if ( iter->terminated )
+			continue;
+		is_others = true;
+	}
+	kthread_mutex_unlock(&thread->process->threadlock);
+
+	if ( (flags & EXIT_THREAD_ONLY_IF_OTHERS) && !is_others )
+		return errno = ESRCH, -1;
+
+	if ( flags & EXIT_THREAD_UNMAP &&
+	     Page::IsAligned((uintptr_t) extended.unmap_from) &&
+	     extended.unmap_size )
+	{
+		ScopedLock lock(&process->segment_lock);
+		Memory::UnmapMemory(process, (uintptr_t) extended.unmap_from,
+		                                         extended.unmap_size);
+	}
+
+	if ( flags & EXIT_THREAD_ZERO )
+		ZeroUser(extended.zero_from, extended.zero_size);
+
+	if ( !is_others )
+		thread->process->Exit(status);
+
+	kthread_exit();
+}
+
 static int sys_kill(pid_t pid, int signum)
 {
 	// Protect the system idle process.
@@ -320,6 +377,7 @@ static int sys_register_signal_handler(sighandler_t sighandler)
 
 void Thread::Init()
 {
+	Syscall::Register(SYSCALL_EXIT_THREAD, (void*) sys_exit_thread);
 	Syscall::Register(SYSCALL_KILL, (void*) sys_kill);
 	Syscall::Register(SYSCALL_RAISE, (void*) sys_raise);
 	Syscall::Register(SYSCALL_REGISTER_SIGNAL_HANDLER, (void*) sys_register_signal_handler);
diff --git a/libc/Makefile b/libc/Makefile
index 323cb714..e9b4ac60 100644
--- a/libc/Makefile
+++ b/libc/Makefile
@@ -499,6 +499,7 @@ unistd/execv.o \
 unistd/execvpe.o \
 unistd/execvp.o \
 unistd/_exit.o \
+unistd/exit_thread.o \
 unistd/faccessat.o \
 unistd/fchdirat.o \
 unistd/fchdir.o \
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index ebe357dd..ad667b0e 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -36,6 +36,7 @@
 #if defined(_SORTIX_SOURCE)
 #include <stdarg.h>
 #include <stdint.h>
+#include <sortix/exit.h>
 #include <sortix/fork.h>
 __BEGIN_DECLS
 #ifndef __time_t_defined
@@ -401,6 +402,7 @@ ssize_t write(int, const void*, size_t);
 #if defined(_SORTIX_SOURCE)
 int alarmns(const struct timespec* delay, struct timespec* odelay);
 int execvpe(const char*, char* const [], char* const []);
+int exit_thread(int, int, const struct exit_thread*);
 int memstat(size_t* memused, size_t* memtotal);
 int mkpartition(int fd, off_t start, off_t length);
 pid_t sfork(int flags);
diff --git a/libc/unistd/exit_thread.cpp b/libc/unistd/exit_thread.cpp
new file mode 100644
index 00000000..ea73936a
--- /dev/null
+++ b/libc/unistd/exit_thread.cpp
@@ -0,0 +1,35 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2013, 2014.
+
+    This file is part of Sortix.
+
+    Sortix is free software: you can redistribute it and/or modify it under the
+    terms of the GNU General Public License as published by the Free Software
+    Foundation, either version 3 of the License, or (at your option) any later
+    version.
+
+    Sortix 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 General Public License for more
+    details.
+
+    You should have received a copy of the GNU General Public License along with
+    Sortix. If not, see <http://www.gnu.org/licenses/>.
+
+    unistd/exit_thread.cpp
+    Destroys the current thread immediately with no clean up.
+
+*******************************************************************************/
+
+#include <sys/syscall.h>
+
+#include <unistd.h>
+
+DEFN_SYSCALL3(int, sys_exit_thread, SYSCALL_EXIT_THREAD, int, int, const struct exit_thread*);
+
+extern "C"
+int exit_thread(int status, int flags, const struct exit_thread* extended)
+{
+	return sys_exit_thread(status, flags, extended);
+}