diff --git a/libc/config/linux/syscall_numbers.h.inc b/libc/config/linux/syscall_numbers.h.inc
--- a/libc/config/linux/syscall_numbers.h.inc
+++ b/libc/config/linux/syscall_numbers.h.inc
@@ -422,6 +422,10 @@
 #define SYS_futex __NR_futex
 #endif
 
+#ifdef __NR_futex_time64
+#define SYS_futex_time64 __NR_futex_time64
+#endif
+
 #ifdef __NR_futimesat
 #define SYS_futimesat __NR_futimesat
 #endif
diff --git a/libc/src/__support/File/linux_file.cpp b/libc/src/__support/File/linux_file.cpp
--- a/libc/src/__support/File/linux_file.cpp
+++ b/libc/src/__support/File/linux_file.cpp
@@ -68,12 +68,16 @@
 #ifdef SYS_lseek
   int ret = __llvm_libc::syscall_impl(SYS_lseek, lf->get_fd(), offset, whence);
   result = ret;
+#elif defined(SYS_llseek)
+  long ret =
+      __llvm_libc::syscall_impl(SYS_llseek, lf->get_fd(), offset, whence);
+  result = ret;
 #elif defined(SYS__llseek)
   long result;
   int ret = __llvm_libc::syscall_impl(SYS__llseek, lf->get_fd(), offset >> 32,
                                       offset, &result, whence);
 #else
-#error "lseek and _llseek syscalls not available to perform a seek operation."
+#error "lseek, llseek and _llseek syscalls not available."
 #endif
 
   if (ret < 0)
diff --git a/libc/src/__support/threads/linux/mutex.h b/libc/src/__support/threads/linux/mutex.h
--- a/libc/src/__support/threads/linux/mutex.h
+++ b/libc/src/__support/threads/linux/mutex.h
@@ -76,9 +76,17 @@
         // futex syscall will block if the futex data is still
         // `LockState::Waiting` (the 4th argument to the syscall function
         // below.)
+#if SYS_futex
         __llvm_libc::syscall_impl(SYS_futex, &futex_word.val,
                                   FUTEX_WAIT_PRIVATE,
                                   FutexWordType(LockState::Waiting), 0, 0, 0);
+#elif defined(SYS_futex_time64)
+        __llvm_libc::syscall_impl(SYS_futex_time64, &futex_word.val,
+                                  FUTEX_WAIT_PRIVATE,
+                                  FutexWordType(LockState::Waiting), 0, 0, 0);
+#else
+#error "futex and futex_time64 syscalls not available."
+#endif
         was_waiting = true;
         // Once woken up/unblocked, try everything all over.
         continue;
@@ -91,8 +99,16 @@
           // we will wait for the futex to be woken up. Note again that the
           // following syscall will block only if the futex data is still
           // `LockState::Waiting`.
+#if SYS_futex
           __llvm_libc::syscall_impl(SYS_futex, &futex_word, FUTEX_WAIT_PRIVATE,
                                     FutexWordType(LockState::Waiting), 0, 0, 0);
+#elif defined(SYS_futex_time64)
+          __llvm_libc::syscall_impl(SYS_futex_time64, &futex_word,
+                                    FUTEX_WAIT_PRIVATE,
+                                    FutexWordType(LockState::Waiting), 0, 0, 0);
+#else
+#error "futex and futex_time64 syscalls not available."
+#endif
           was_waiting = true;
         }
         continue;
@@ -109,8 +125,15 @@
       if (futex_word.compare_exchange_strong(mutex_status,
                                              FutexWordType(LockState::Free))) {
         // If any thread is waiting to be woken up, then do it.
+#if SYS_futex
         __llvm_libc::syscall_impl(SYS_futex, &futex_word, FUTEX_WAKE_PRIVATE, 1,
                                   0, 0, 0);
+#elif defined(SYS_futex_time64)
+        __llvm_libc::syscall_impl(SYS_futex_time64, &futex_word,
+                                  FUTEX_WAKE_PRIVATE, 1, 0, 0, 0);
+#else
+#error "futex and futex_time64 syscalls not available."
+#endif
         return MutexError::NONE;
       }
 
diff --git a/libc/src/sys/sendfile/linux/sendfile.cpp b/libc/src/sys/sendfile/linux/sendfile.cpp
--- a/libc/src/sys/sendfile/linux/sendfile.cpp
+++ b/libc/src/sys/sendfile/linux/sendfile.cpp
@@ -19,8 +19,15 @@
 
 LLVM_LIBC_FUNCTION(ssize_t, sendfile,
                    (int out_fd, int in_fd, off_t *offset, size_t count)) {
+#ifdef SYS_sendfile
   long ret =
       __llvm_libc::syscall_impl(SYS_sendfile, in_fd, out_fd, offset, count);
+#elif defined(SYS_sendfile64)
+  long ret =
+      __llvm_libc::syscall_impl(SYS_sendfile64, in_fd, out_fd, offset, count);
+#else
+#error "sendfile and sendfile64 syscalls not available."
+#endif
   if (ret < 0) {
     libc_errno = -ret;
     return -1;
diff --git a/libc/src/sys/wait/linux/wait.cpp b/libc/src/sys/wait/linux/wait.cpp
--- a/libc/src/sys/wait/linux/wait.cpp
+++ b/libc/src/sys/wait/linux/wait.cpp
@@ -10,6 +10,7 @@
 
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/common.h"
+#include "src/__support/libc_assert.h"
 
 #include "src/errno/libc_errno.h"
 #include <sys/syscall.h> // For syscall numbers.
@@ -21,7 +22,21 @@
 // functionality and standard compliance in future.
 
 LLVM_LIBC_FUNCTION(pid_t, wait, (int *wait_status)) {
+#if SYS_wait4
   pid_t pid = __llvm_libc::syscall_impl(SYS_wait4, -1, wait_status, 0, 0);
+#elif defined(SYS_waitpid)
+  pid_t pid = __llvm_libc::syscall_impl(SYS_waitpid, -1, wait_status, 0);
+#elif defined(SYS_waitid)
+  siginfo_t info;
+  if (__llvm_libc::syscall_impl(SYS_waitid, P_ALL, 0, &info, WEXITED, 0) == -1)
+    // TODO: what's the libc_errno here?
+    return -1;
+  LIBC_ASSERT(wait_status != nullptr);
+  *wait_status = info.si_status;
+  pid_t pid = info.si_pid;
+#else
+#error "waitpid, wait4 and waitid syscalls not available."
+#endif
   if (pid < 0) {
     // Error case, a child process was not created.
     libc_errno = -pid;
diff --git a/libc/src/sys/wait/linux/wait4.cpp b/libc/src/sys/wait/linux/wait4.cpp
--- a/libc/src/sys/wait/linux/wait4.cpp
+++ b/libc/src/sys/wait/linux/wait4.cpp
@@ -10,6 +10,7 @@
 
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/common.h"
+#include "src/__support/libc_assert.h"
 
 #include "src/errno/libc_errno.h"
 #include <sys/syscall.h> // For syscall numbers.
@@ -20,7 +21,27 @@
 LLVM_LIBC_FUNCTION(pid_t, wait4,
                    (pid_t pid, int *wait_status, int options,
                     struct rusage *usage)) {
+#if SYS_wait4
   pid = __llvm_libc::syscall_impl(SYS_wait4, pid, wait_status, options, usage);
+#elif defined(SYS_waitpid)
+  pid_t pid = __llvm_libc::syscall_impl(SYS_waitpid, pid, wait_status, options);
+  if (pid > 0) {
+    if (usage != nullptr && (getrusage(info.si_pid, usage) == -1))
+      // TODO: what's the libc_errno here?
+      return -1;
+  }
+#elif defined(SYS_waitid)
+  siginfo_t info;
+  if (__llvm_libc::syscall_impl(SYS_waitid, P_PID, pid, &info,
+                                options | WEXITED | WSTOPPED | WCONTINUED,
+                                usage) == -1)
+    return -1;
+  LIBC_ASSERT(wait_status != nullptr);
+  *wait_status = info.si_status;
+  pid = info.si_pid;
+#else
+#error "waitpid, wait4 and waitid syscalls not available."
+#endif
   if (pid < 0) {
     libc_errno = -pid;
     return -1;
diff --git a/libc/src/sys/wait/linux/waitpid.cpp b/libc/src/sys/wait/linux/waitpid.cpp
--- a/libc/src/sys/wait/linux/waitpid.cpp
+++ b/libc/src/sys/wait/linux/waitpid.cpp
@@ -10,6 +10,7 @@
 
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/common.h"
+#include "src/__support/libc_assert.h"
 
 #include "src/errno/libc_errno.h"
 #include <sys/syscall.h> // For syscall numbers.
@@ -18,7 +19,22 @@
 namespace __llvm_libc {
 
 LLVM_LIBC_FUNCTION(pid_t, waitpid, (pid_t pid, int *wait_status, int options)) {
+#if SYS_waitpid
+  pid = __llvm_libc::syscall_impl(SYS_waitpid, pid, wait_status, options);
+#elif defined(SYS_wait4)
   pid = __llvm_libc::syscall_impl(SYS_wait4, pid, wait_status, options, 0);
+#elif defined(SYS_waitid)
+  siginfo_t info;
+  if (__llvm_libc::syscall_impl(SYS_waitid, P_PID, pid, &info, options, 0) ==
+      -1)
+    // TODO: what's the libc_errno here?
+    return -1;
+  LIBC_ASSERT(wait_status != nullptr);
+  *wait_status = info.si_status;
+  pid = info.si_pid;
+#else
+#error "waitpid, wait4 and waitid syscalls not available."
+#endif
   if (pid < 0) {
     libc_errno = -pid;
     return -1;
diff --git a/libc/src/unistd/linux/dup2.cpp b/libc/src/unistd/linux/dup2.cpp
--- a/libc/src/unistd/linux/dup2.cpp
+++ b/libc/src/unistd/linux/dup2.cpp
@@ -27,7 +27,13 @@
   // separately before making the dup3 syscall.
   if (oldfd == newfd) {
     // Check if oldfd is actually a valid file descriptor.
+#if SYS_fcntl
     long ret = __llvm_libc::syscall_impl(SYS_fcntl, oldfd, F_GETFD);
+#elif defined(SYS_fcntl64)
+    long ret = __llvm_libc::syscall_impl(SYS_fcntl64, oldfd, F_GETFD);
+#else
+#error "SYS_fcntl and SYS_fcntl64 syscalls not available."
+#endif
     if (ret >= 0)
       return oldfd;
     libc_errno = -ret;
diff --git a/libc/src/unistd/linux/ftruncate.cpp b/libc/src/unistd/linux/ftruncate.cpp
--- a/libc/src/unistd/linux/ftruncate.cpp
+++ b/libc/src/unistd/linux/ftruncate.cpp
@@ -18,7 +18,14 @@
 namespace __llvm_libc {
 
 LLVM_LIBC_FUNCTION(int, ftruncate, (int fd, off_t len)) {
+#ifdef SYS_ftruncate
   int ret = __llvm_libc::syscall_impl(SYS_ftruncate, fd, len);
+#elif defined(SYS_ftruncate64)
+  int ret = __llvm_libc::syscall_impl(SYS_ftruncate64, fd, len);
+#else
+#error "ftruncate and ftruncate64 syscalls not available."
+#endif
+
   if (ret < 0) {
     libc_errno = -ret;
     return -1;
diff --git a/libc/src/unistd/linux/lseek.cpp b/libc/src/unistd/linux/lseek.cpp
--- a/libc/src/unistd/linux/lseek.cpp
+++ b/libc/src/unistd/linux/lseek.cpp
@@ -22,11 +22,14 @@
 #ifdef SYS_lseek
   long ret = __llvm_libc::syscall_impl(SYS_lseek, fd, offset, whence);
   result = ret;
+#elif defined(SYS_llseek)
+  long ret = __llvm_libc::syscall_impl(SYS_llseek, fd, offset, whence);
+  result = ret;
 #elif defined(SYS__llseek)
-  long ret = __llvm_libc::syscall_impl(SYS__llseek, fd, offset >> 32, offset,
-                                       &result, whence);
+  int ret = __llvm_libc::syscall_impl(SYS__llseek, fd, offset >> 32, offset,
+                                      &result, whence);
 #else
-#error "lseek and _llseek syscalls not available."
+#error "lseek, llseek and _llseek syscalls not available."
 #endif
 
   if (ret < 0) {
diff --git a/libc/src/unistd/linux/truncate.cpp b/libc/src/unistd/linux/truncate.cpp
--- a/libc/src/unistd/linux/truncate.cpp
+++ b/libc/src/unistd/linux/truncate.cpp
@@ -18,7 +18,13 @@
 namespace __llvm_libc {
 
 LLVM_LIBC_FUNCTION(int, truncate, (const char *path, off_t len)) {
+#ifdef SYS_truncate
   int ret = __llvm_libc::syscall_impl(SYS_truncate, path, len);
+#elif defined(SYS_truncate64)
+  int ret = __llvm_libc::syscall_impl(SYS_truncate64, path, len);
+#else
+#error "truncate and truncate64 syscalls not available."
+#endif
   if (ret < 0) {
     libc_errno = -ret;
     return -1;