diff --git a/ChangeLog.md b/ChangeLog.md
index 0c346f8ff4088..8be4b342b5bac 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -39,6 +39,8 @@ See docs/process.md for more on how version tagging works.
 - The getWasmTableEntry/setWasmTableEntry library function are no longer
   included by default.  Add them to `DEFAULT_LIBRARY_FUNCS_TO_INCLUDE` or
   `EXPORTED_RUNTIME_METHODS` if you want to use them outside of JS library code.
+- The type of `time_t` was restored 64-bit after being converted to 32-bit in
+  3.1.11. (#17401)
 
 3.1.15 - 07/01/2022
 -------------------
diff --git a/system/lib/libc/emscripten_time.c b/system/lib/libc/emscripten_time.c
index 6f150c1229dfd..11b945aa72a0f 100644
--- a/system/lib/libc/emscripten_time.c
+++ b/system/lib/libc/emscripten_time.c
@@ -19,8 +19,12 @@ __attribute__((__weak__)) int   daylight = 0;
 __attribute__((__weak__)) char *tzname[2] = { 0, 0 };
 
 void _tzset_js(long* timezone, int* daylight, char** tzname);
-time_t _timegm_js(struct tm *tm);
-time_t _mktime_js(struct tm *tm);
+// Declare these functions `int` rather than time_t to avoid int64 at the wasm
+// boundary (avoids 64-bit complexity at the boundary when WASM_BIGINT is
+// missing).
+// TODO(sbc): Covert back to `time_t` before 2038 ...
+int _timegm_js(struct tm *tm);
+int _mktime_js(struct tm *tm);
 void _localtime_js(const time_t *restrict t, struct tm *restrict tm);
 void _gmtime_js(const time_t *restrict t, struct tm *restrict tm);
 double _emscripten_date_now();
diff --git a/system/lib/libc/musl/arch/emscripten/bits/alltypes.h b/system/lib/libc/musl/arch/emscripten/bits/alltypes.h
index e90252190f63c..1f7a6718233bc 100644
--- a/system/lib/libc/musl/arch/emscripten/bits/alltypes.h
+++ b/system/lib/libc/musl/arch/emscripten/bits/alltypes.h
@@ -78,7 +78,7 @@ typedef long double double_t;
 #endif
 
 #if defined(__NEED_time_t) && !defined(__DEFINED_time_t)
-typedef int time_t; /* XXX EMSCRIPTEN: ensure it's always 32-bits even in wasm64 */
+typedef _Int64 time_t;
 #define __DEFINED_time_t
 #endif
 
diff --git a/system/lib/libc/musl/include/inttypes.h b/system/lib/libc/musl/include/inttypes.h
index fd012b0f33964..90c35c8664ae8 100644
--- a/system/lib/libc/musl/include/inttypes.h
+++ b/system/lib/libc/musl/include/inttypes.h
@@ -22,14 +22,14 @@ uintmax_t strtoumax(const char *__restrict, char **__restrict, int);
 intmax_t wcstoimax(const wchar_t *__restrict, wchar_t **__restrict, int);
 uintmax_t wcstoumax(const wchar_t *__restrict, wchar_t **__restrict, int);
 
-#if UINTPTR_MAX == UINT64_MAX
-#define __PRI64  "l"
-#define __PRIPTR "l"
-#elif defined(__EMSCRIPTEN__)
+#if defined(__EMSCRIPTEN__)
 // Under emscripten __PTRDIFF_TYPE__ and therefor intptr_t are defined to
 // be `long int` even on wasm32.
 #define __PRI64  "ll"
 #define __PRIPTR "l"
+#elif UINTPTR_MAX == UINT64_MAX
+#define __PRI64  "l"
+#define __PRIPTR "l"
 #else
 #define __PRI64  "ll"
 #define __PRIPTR ""
diff --git a/system/lib/libc/musl/src/time/clock.c b/system/lib/libc/musl/src/time/clock.c
index b2ce32ffe5f48..6724012b92ef6 100644
--- a/system/lib/libc/musl/src/time/clock.c
+++ b/system/lib/libc/musl/src/time/clock.c
@@ -1,12 +1,6 @@
 #include <time.h>
 #include <limits.h>
 
-#ifdef __EMSCRIPTEN__
-#define TIME_T_MAX INT_MAX
-#else
-#define TIME_T_MAX LONG_MAX
-#endif
-
 clock_t clock()
 {
 	struct timespec ts;
@@ -14,7 +8,7 @@ clock_t clock()
 	if (__clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts))
 		return -1;
 
-	if (ts.tv_sec > TIME_T_MAX/1000000
+	if (ts.tv_sec > LONG_MAX/1000000
 	 || ts.tv_nsec/1000 > LONG_MAX-1000000*ts.tv_sec)
 		return -1;
 
diff --git a/tests/reference_struct_info.json b/tests/reference_struct_info.json
index 610b43363cd41..3acc4fc0db4f5 100644
--- a/tests/reference_struct_info.json
+++ b/tests/reference_struct_info.json
@@ -1410,30 +1410,30 @@
             "sin6_scope_id": 24
         },
         "stat": {
-            "__size__": 88,
+            "__size__": 112,
             "__st_dev_padding": 4,
             "__st_ino_truncated": 8,
             "__st_rdev_padding": 32,
             "st_atim": {
-                "__size__": 8,
-                "tv_nsec": 60,
+                "__size__": 16,
+                "tv_nsec": 64,
                 "tv_sec": 56
             },
             "st_blksize": 48,
             "st_blocks": 52,
             "st_ctim": {
-                "__size__": 8,
-                "tv_nsec": 76,
-                "tv_sec": 72
+                "__size__": 16,
+                "tv_nsec": 96,
+                "tv_sec": 88
             },
             "st_dev": 0,
             "st_gid": 24,
-            "st_ino": 80,
+            "st_ino": 104,
             "st_mode": 12,
             "st_mtim": {
-                "__size__": 8,
-                "tv_nsec": 68,
-                "tv_sec": 64
+                "__size__": 16,
+                "tv_nsec": 80,
+                "tv_sec": 72
             },
             "st_nlink": 16,
             "st_rdev": 28,
@@ -1461,8 +1461,8 @@
             "timeSpentInStatus": 16
         },
         "timespec": {
-            "__size__": 8,
-            "tv_nsec": 4,
+            "__size__": 16,
+            "tv_nsec": 8,
             "tv_sec": 0
         },
         "tm": {
diff --git a/tests/utime/test_utime.c b/tests/utime/test_utime.c
index ebc78c5dc6656..76c37e56953e1 100644
--- a/tests/utime/test_utime.c
+++ b/tests/utime/test_utime.c
@@ -7,6 +7,7 @@
 
 #include <assert.h>
 #include <errno.h>
+#include <inttypes.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -51,9 +52,9 @@ void test() {
   stat("writeable", &s);
   assert(s.st_atime == s.st_mtime);
   time_t diff = s.st_atime - now;
-  if (abs(diff) > 5) {
-    fprintf(stderr, "st_atime: %i, now: %i, diff: %i\n ", s.st_atime, now, diff);
-    assert(abs(diff) <= 5);
+  if (llabs(diff) > 5) {
+    fprintf(stderr, "st_atime: %" PRId64 ", now: %" PRId64 ", diff: %" PRId64 "\n ", s.st_atime, now, diff);
+    assert(llabs(diff) <= 5);
   }
 
   // write permissions aren't checked when setting node