diff --git a/libc/include/llvm-libc-types/time_t.h b/libc/include/llvm-libc-types/time_t.h
--- a/libc/include/llvm-libc-types/time_t.h
+++ b/libc/include/llvm-libc-types/time_t.h
@@ -9,6 +9,10 @@
 #ifndef __LLVM_LIBC_TYPES_TIME_T_H__
 #define __LLVM_LIBC_TYPES_TIME_T_H__
 
+#if (defined(__arm__) || defined(_M_ARM))
 typedef __INTPTR_TYPE__ time_t;
+#else
+typedef __INT64_TYPE__ time_t;
+#endif
 
 #endif // __LLVM_LIBC_TYPES_TIME_T_H__
diff --git a/libc/src/time/linux/clockGetTimeImpl.h b/libc/src/time/linux/clockGetTimeImpl.h
--- a/libc/src/time/linux/clockGetTimeImpl.h
+++ b/libc/src/time/linux/clockGetTimeImpl.h
@@ -14,6 +14,7 @@
 #include "src/__support/error_or.h"
 #include "src/errno/libc_errno.h"
 
+#include <stdint.h>      // For int64_t.
 #include <sys/syscall.h> // For syscall numbers.
 #include <time.h>
 
@@ -27,12 +28,12 @@
                                            static_cast<long>(clockid),
                                            reinterpret_cast<long>(ts));
 #elif defined(SYS_clock_gettime64)
-  struct timespec64 ts64;
+  static_assert(
+      sizeof(time_t) == sizeof(int64_t),
+      "SYS_clock_gettime64 requires struct timespec with 64-bit members.");
   int ret = __llvm_libc::syscall_impl<int>(SYS_clock_gettime64,
                                            static_cast<long>(clockid),
-                                           reinterpret_cast<long>(&ts64));
-  ts->tv_sec = static_cast<time_t>(ts64.tv_sec);
-  ts->tv_nsec = static_cast<long>(ts64.tv_nsec);
+                                           reinterpret_cast<long>(ts));
 #else
 #error "SYS_clock_gettime and SYS_clock_gettime64 syscalls not available."
 #endif
diff --git a/libc/src/time/linux/nanosleep.cpp b/libc/src/time/linux/nanosleep.cpp
--- a/libc/src/time/linux/nanosleep.cpp
+++ b/libc/src/time/linux/nanosleep.cpp
@@ -12,6 +12,7 @@
 #include "src/__support/common.h"
 #include "src/errno/libc_errno.h"
 
+#include <stdint.h>      // For int64_t.
 #include <sys/syscall.h> // For syscall numbers.
 
 namespace __llvm_libc {
@@ -21,8 +22,11 @@
 #if SYS_nanosleep
   int ret = __llvm_libc::syscall_impl<int>(SYS_nanosleep, req, rem);
 #elif defined(SYS_clock_nanosleep_time64)
-  int ret =
-      __llvm_libc::syscall_impl<int>(SYS_clock_nanosleep_time64, req, rem);
+  static_assert(
+      sizeof(time_t) == sizeof(int64_t),
+      "SYS_clock_gettime64 requires struct timespec with 64-bit members.");
+  int ret = __llvm_libc::syscall_impl<int>(SYS_clock_nanosleep_time64,
+                                           CLOCK_REALTIME, 0, req, rem);
 #else
 #error "SYS_nanosleep and SYS_clock_nanosleep_time64 syscalls not available."
 #endif