diff --git a/arch/aarch64.c b/arch/aarch64.c
index ba8436b..0fd1d87 100644
--- a/arch/aarch64.c
+++ b/arch/aarch64.c
@@ -294,4 +294,82 @@ ssize_t recvfrom(int sockfd, const void* buf, size_t size, int flags, const void
   return rtn;
 }
 
+
+int clock_settime(clockid_t clockid, const struct timespec *tp) {
+  long int rtn;
+  asm volatile (
+    // Assembly Instructions
+    "mov x8, #112\n"  // Syscall number for 'listen' is 201 in AArch64
+    "mov x0, %1\n"    // fd
+    "mov x1, %2\n"    // backlog
+    "svc #0\n"        // Make the syscall
+    "mov %0, x0\n"    // save return value
+    // Output operands
+    : "=r" (rtn)
+    // Input operand
+    : "r" ((int64_t)clockid), "r"(tp)
+    // Clobbered registers
+    : "x0", "x1", "x8"
+  );
+  return (int32_t)rtn;
+}
+
+int clock_gettime(clockid_t clockid, struct timespec *tp) {
+  long int rtn;
+  asm volatile (
+    // Assembly Instructions
+    "mov x8, #113\n"  // Syscall number for 'listen' is 201 in AArch64
+    "mov x0, %1\n"    // fd
+    "mov x1, %2\n"    // backlog
+    "svc #0\n"        // Make the syscall
+    "mov %0, x0\n"    // save return value
+    // Output operands
+    : "=r" (rtn)
+    // Input operand
+    : "r" ((int64_t)clockid), "r"(tp)
+    // Clobbered registers
+    : "x0", "x1", "x8", "memory"
+  );
+  return (int32_t)rtn;
+}
+
+int clock_getres(clockid_t clockid, struct timespec *res) {
+  long int rtn;
+  asm volatile (
+    // Assembly Instructions
+    "mov x8, #114\n"  // Syscall number for 'listen' is 201 in AArch64
+    "mov x0, %1\n"    // fd
+    "mov x1, %2\n"    // backlog
+    "svc #0\n"        // Make the syscall
+    "mov %0, x0\n"    // save return value
+    // Output operands
+    : "=r" (rtn)
+    // Input operand
+    : "r" ((int64_t)clockid), "r"(res)
+    // Clobbered registers
+    : "x0", "x1", "x8", "memory"
+  );
+  return (int32_t)rtn;
+}
+
+int clock_nanosleep(clockid_t clockid, int flags, const struct timespec *t, struct timespec* remain) {
+  long int rtn;
+  asm volatile (
+    // Assembly Instructions
+    "mov x8, #115\n"  // Syscall number for 'listen' is 201 in AArch64
+    "mov x0, %1\n"    // fd
+    "mov x1, %2\n"    // backlog
+    "mov x2, %3\n"    // backlog
+    "svc #0\n"        // Make the syscall
+    "mov %0, x0\n"    // save return value
+    // Output operands
+    : "=r" (rtn)
+    // Input operand
+    : "r" ((int64_t)clockid), "r"((int64_t)flags), "r"(t), "r"(remain)
+    // Clobbered registers
+    : "x0", "x1", "x8", "memory"
+  );
+  return (int32_t)rtn;
+}
+
 #endif
diff --git a/arch/mips.c b/arch/mips.c
index 0ef5e37..4d5f52a 100644
--- a/arch/mips.c
+++ b/arch/mips.c
@@ -242,4 +242,63 @@ ssize_t recvfrom(int sockfd, const void* buf, size_t size, int flags, const void
   return rtn;
 }
 
+int clock_settime(clockid_t clockid, const struct timespec *tp){
+  int rtn = 0;
+  asm volatile ( 
+    "move $a0, %1\n"
+    "move $a1, %2\n"
+    "li $v0, 4262\n"
+    "syscall\n"
+    "move %0, $v0\n"
+    : "=r"(rtn)
+    : "r"(clockid), "r"(tp)
+    : "a0", "a1", "v0"
+  );
+  return rtn;
+}
+int clock_gettime(clockid_t clockid, struct timespec *tp){
+  int rtn = 0;
+  asm volatile ( 
+    "move $a0, %1\n"
+    "move $a1, %2\n"
+    "li $v0, 4263\n"
+    "syscall\n"
+    "move %0, $v0\n"
+    : "=r"(rtn)
+    : "r"(clockid), "r"(tp)
+    : "a0", "a1", "v0", "memory"
+  );
+  return rtn;
+}
+int clock_getres(clockid_t clockid, struct timespec *res){
+  int rtn = 0;
+  asm volatile ( 
+    "move $a0, %1\n"
+    "move $a1, %2\n"
+    "li $v0, 4264\n"
+    "syscall\n"
+    "move %0, $v0\n"
+    : "=r"(rtn)
+    : "r"(clockid), "r"(res)
+    : "a0", "a1", "v0", "memory"
+  );
+  return rtn;
+}
+int clock_nanosleep(clockid_t clockid, int flags, const struct timespec *t, struct timespec* remain){
+  int rtn = 0;
+  asm volatile (
+    "move $a0, %1\n"
+    "move $a1, %2\n"
+    "move $a2, %3\n"
+    "move $a3, %4\n"
+    "li $v0, 4265\n"
+    "syscall\n"
+    "move %0, $v0\n"
+    : "=r"(rtn)
+    : "r"(clockid), "r"(flags), "r"(t), "r"(remain)
+    : "a0", "a1", "a2", "a3", "v0", "memory"
+  );
+  return rtn;
+}
+
 #endif
diff --git a/arch/x86_64.c b/arch/x86_64.c
index 28378c8..24c4f4c 100644
--- a/arch/x86_64.c
+++ b/arch/x86_64.c
@@ -192,4 +192,53 @@ ssize_t recvfrom(int fd, const void* buf, size_t size, int flags, const void* so
   return nrecv;
 }
 
+#define SYS_CLOCK_SETTIME 227
+int clock_settime(clockid_t clockid, const struct timespec *tp) {
+  int rtn;
+  asm volatile(
+    "syscall\n"
+    : "=a"(rtn)
+    : "a"(SYS_CLOCK_SETTIME), "D"(clockid), "S"(tp)
+    : "rcx", "r11"
+  );
+  return rtn;
+}
+
+#define SYS_CLOCK_GETTIME 228
+int clock_gettime(clockid_t clockid, struct timespec *tp) {
+  int rtn;
+  asm volatile(
+    "syscall\n"
+    : "=a"(rtn)
+    : "a"(SYS_CLOCK_GETTIME), "D"(clockid), "S"(tp)
+    : "rcx", "r11", "memory"
+  );
+  return rtn;
+}
+
+#define SYS_CLOCK_GETRES 229
+int clock_getres(clockid_t clockid, struct timespec *res){
+  int rtn;
+  asm volatile(
+    "syscall\n"
+    : "=a"(rtn)
+    : "a"(SYS_CLOCK_GETRES), "D"(clockid), "S"(res)
+    : "rcx", "r11", "memory"
+  );
+  return rtn;
+}
+
+#define SYS_CLOCK_NANOSLEEP 230
+int clock_nanosleep(clockid_t clockid, int flags, const struct timespec *t, struct timespec* remain){
+  int rtn;
+  asm volatile(
+    "mov %5, %%r10\n"
+    "syscall\n"
+    : "=a"(rtn)
+    : "a"(SYS_CLOCK_NANOSLEEP), "D"(clockid), "S"(flags), "d"(t), "r"(remain)
+    : "rcx", "r11", "memory"
+  );
+  return rtn;
+}
+
 #endif /* ifdef __x86_64__ */
diff --git a/buildtest.c b/buildtest.c
index 17bed6c..f439db2 100644
--- a/buildtest.c
+++ b/buildtest.c
@@ -50,6 +50,14 @@ int main() {
   } else {
     write(STDOUT, "Could not open /proc/version\n", 29);
   }
+
+  // Test sleep
+  write(STDOUT, "Sleeping for 5 secs\n", 20);
+  struct timespec sleeptime;
+  sleeptime.tv_sec = 5;
+  while (nanosleep(&sleeptime, &sleeptime) != 0) {}
+  write(STDOUT, "DONE\n", 5);
+
   return 69;
 }
 
diff --git a/int.h b/int.h
index caf7cf6..7c03f86 100644
--- a/int.h
+++ b/int.h
@@ -33,6 +33,13 @@ typedef uintptr_t size_t;
 typedef uint32_t socklen_t;
 typedef uint32_t pid_t;
 
+typedef long time_t;
+typedef int clockid_t;
+struct timespec {
+  time_t  tv_sec;         /* seconds */
+  long    tv_nsec;        /* nanoseconds */
+};
+
 // Compile time tests in supported compilers
 #ifdef __SIZEOF_SHORT__
 #if __SIZEOF_SHORT__ != 2
diff --git a/sys.h b/sys.h
index c2781bc..2405368 100644
--- a/sys.h
+++ b/sys.h
@@ -128,9 +128,22 @@ typedef unsigned short  sa_family_t;
 #define SO_PASSCRED 17
 #define SO_PEERCRED 18
 
+// Time management
+#define CLOCK_REALTIME           0
+#define CLOCK_MONOTONIC          1
+#define CLOCK_PROCESS_CPUTIME_ID 2
+#define CLOCK_THREAD_CPUTIME_ID  3
+#define TIMER_ABSTIME 0x01
+int clock_settime(clockid_t clockid, const struct timespec *tp);
+int clock_gettime(clockid_t clockid, struct timespec *tp);
+int clock_getres(clockid_t clockid, struct timespec *res);
+int clock_nanosleep(clockid_t clockid, int flags, const struct timespec *t, struct timespec* remain);
+#define nanosleep(t, remain) clock_nanosleep(CLOCK_MONOTONIC, 0, t, remain)
+
 uint32_t fork();
 
 // Provide memset for clang
+// TODO: move this (and start code?) to separate .c file
 void *memset(void* s, int c, unsigned long n) {
   int8_t* mem = s;
   for(long int i = 0; i < n; ++i) mem[i] = c;