diff --git a/libc-bottom-half/cloudlibc/src/libc/fcntl/fcntl.c b/libc-bottom-half/cloudlibc/src/libc/fcntl/fcntl.c
index f8673576b..06b728836 100644
--- a/libc-bottom-half/cloudlibc/src/libc/fcntl/fcntl.c
+++ b/libc-bottom-half/cloudlibc/src/libc/fcntl/fcntl.c
@@ -9,12 +9,30 @@
 
 int fcntl(int fildes, int cmd, ...) {
   switch (cmd) {
-    case F_GETFD:
-      // Act as if the close-on-exec flag is always set.
-      return FD_CLOEXEC;
-    case F_SETFD:
-      // The close-on-exec flag is ignored.
+    case F_GETFD: {
+      __wasi_fdflagsext_t flags;
+      __wasi_errno_t error = __wasi_fd_fdflags_get(fildes, &flags);
+      if (error != 0) {
+        errno = error;
+        return -1;
+      }
+      return flags & __WASI_FDFLAGSEXT_CLOEXEC ? FD_CLOEXEC : 0;
+    }
+    case F_SETFD: {
+      va_list ap;
+      va_start(ap, cmd);
+      int flags = va_arg(ap, int);
+      va_end(ap);
+
+      __wasi_fdflagsext_t fd_flags = flags | FD_CLOEXEC ? __WASI_FDFLAGSEXT_CLOEXEC : 0;
+      __wasi_errno_t error =
+          __wasi_fd_fdflags_set(fildes, fd_flags);
+      if (error != 0) {
+        errno = error;
+        return -1;
+      }
       return 0;
+    }
     case F_GETFL: {
       // Obtain the flags and the rights of the descriptor.
       __wasi_fdstat_t fds;
@@ -57,8 +75,14 @@ int fcntl(int fildes, int cmd, ...) {
     }
     case F_DUPFD:
     case F_DUPFD_CLOEXEC: {
+      va_list ap;
+      va_start(ap, cmd);
+      int min_res_fd = va_arg(ap, int);
+      va_end(ap);
+
       int fd;
-      __wasi_errno_t error = __wasi_fd_dup(fildes, &fd);
+      __wasi_bool_t cloexec = cmd == F_DUPFD_CLOEXEC;
+      __wasi_errno_t error = __wasi_fd_dup2(fildes, min_res_fd, cloexec, &fd);
       if (error != 0) {
         errno = error;
         return -1;
diff --git a/libc-bottom-half/cloudlibc/src/libc/fcntl/openat.c b/libc-bottom-half/cloudlibc/src/libc/fcntl/openat.c
index 09cbbf800..4263481c3 100644
--- a/libc-bottom-half/cloudlibc/src/libc/fcntl/openat.c
+++ b/libc-bottom-half/cloudlibc/src/libc/fcntl/openat.c
@@ -20,6 +20,8 @@ static_assert(O_DIRECTORY >> 12 == __WASI_OFLAGS_DIRECTORY, "Value mismatch");
 static_assert(O_EXCL >> 12 == __WASI_OFLAGS_EXCL, "Value mismatch");
 static_assert(O_TRUNC >> 12 == __WASI_OFLAGS_TRUNC, "Value mismatch");
 
+static_assert(O_CLOEXEC >> 24 == __WASI_FDFLAGSEXT_CLOEXEC, "Value mismatch");
+
 int __wasilibc_nocwd_openat_nomode(int fd, const char *path, int oflag) {
   // Compute rights corresponding with the access modes provided.
   // Attempt to obtain all rights, except the ones that contradict the
@@ -65,13 +67,14 @@ int __wasilibc_nocwd_openat_nomode(int fd, const char *path, int oflag) {
 
   // Open file with appropriate rights.
   __wasi_fdflags_t fs_flags = oflag & 0xfff;
+  __wasi_fdflagsext_t fd_flags = oflag >> 24 & 0xff;
   __wasi_rights_t fs_rights_base = max & fsb_cur.fs_rights_inheriting;
   __wasi_rights_t fs_rights_inheriting = fsb_cur.fs_rights_inheriting;
   __wasi_fd_t newfd;
-  error = __wasi_path_open(fd, lookup_flags, path,
+  error = __wasi_path_open2(fd, lookup_flags, path,
                                  (oflag >> 12) & 0xfff,
                                  fs_rights_base, fs_rights_inheriting, fs_flags,
-                                 &newfd);
+                                 fd_flags, &newfd);
   if (error != 0) {
     errno = error;
     return -1;
diff --git a/libc-bottom-half/headers/public/__header_fcntl.h b/libc-bottom-half/headers/public/__header_fcntl.h
index 9f0fcbf8f..c184681ee 100644
--- a/libc-bottom-half/headers/public/__header_fcntl.h
+++ b/libc-bottom-half/headers/public/__header_fcntl.h
@@ -21,10 +21,7 @@
 #define O_SEARCH   (0x08000000)
 #define O_WRONLY   (0x10000000)
 
-/*
- * O_CLOEXEC is defined to be zero, as WASI has no exec-style functions.
- */
-#define O_CLOEXEC  (0)
+#define O_CLOEXEC (__WASI_FDFLAGSEXT_CLOEXEC << 24)
 
 /*
  * O_TTY_INIT is defined to be zero, meaning that WASI implementations are
diff --git a/libc-bottom-half/headers/public/wasi/api_wasix.h b/libc-bottom-half/headers/public/wasi/api_wasix.h
index 5d053df9c..7977184a9 100644
--- a/libc-bottom-half/headers/public/wasi/api_wasix.h
+++ b/libc-bottom-half/headers/public/wasi/api_wasix.h
@@ -1606,6 +1606,18 @@ typedef uint16_t __wasi_eventfdflags_t;
  */
 #define __WASI_EVENTFDFLAGS_SEMAPHORE ((__wasi_eventfdflags_t)(1 << 0))
 
+/**
+ * Actual file descriptor flags. The fdflags type from WASI corresponds to
+ * file status flags, which is why we had to come up with a weird name for
+ * this type.
+ */
+typedef uint16_t __wasi_fdflagsext_t;
+
+/**
+ * Close this file in the child process when spawning one.
+ */
+#define __WASI_FDFLAGSEXT_CLOEXEC ((__wasi_fdflagsext_t)(1 << 0))
+
 /**
  * Rect that represents the TTY.
  */
@@ -3631,6 +3643,15 @@ __wasi_errno_t __wasi_fd_dup(
     __wasi_fd_t fd,
     __wasi_fd_t *retptr0
 ) __attribute__((__warn_unused_result__));
+/**
+ * Atomically duplicate a file handle.
+ */
+__wasi_errno_t __wasi_fd_dup2(
+    __wasi_fd_t fd,
+    __wasi_fd_t min_result_fd,
+    __wasi_bool_t cloexec,
+    __wasi_fd_t *retptr0
+) __attribute__((__warn_unused_result__));
 /**
  * Creates a file handle for event notifications
  * 
@@ -3849,6 +3870,70 @@ _Noreturn void __wasi_stack_restore(
      */
     __wasi_longsize_t val
 );
+/**
+ * Open a file or directory.
+ * The returned file descriptor is not guaranteed to be the lowest-numbered
+ * file descriptor not currently open; it is randomized to prevent
+ * applications from depending on making assumptions about indexes, since this
+ * is error-prone in multi-threaded contexts. The returned file descriptor is
+ * guaranteed to be less than 2**31.
+ * Note: This is similar to `openat` in POSIX.
+ * Recreated in WASIX from the original WASI function to add support for
+ * fdflagsext.
+ * @return
+ * The file descriptor of the file that has been opened.
+ */
+__wasi_errno_t __wasi_path_open2(
+    __wasi_fd_t fd,
+    /**
+     * Flags determining the method of how the path is resolved.
+     */
+    __wasi_lookupflags_t dirflags,
+    /**
+     * The relative path of the file or directory to open, relative to the
+     * `path_open::fd` directory.
+     */
+    const char *path,
+    /**
+     * The method by which to open the file.
+     */
+    __wasi_oflags_t oflags,
+    /**
+     * The initial rights of the newly created file descriptor. The
+     * implementation is allowed to return a file descriptor with fewer rights
+     * than specified, if and only if those rights do not apply to the type of
+     * file being opened.
+     * The *base* rights are rights that will apply to operations using the file
+     * descriptor itself, while the *inheriting* rights are rights that apply to
+     * file descriptors derived from it.
+     */
+    __wasi_rights_t fs_rights_base,
+    __wasi_rights_t fs_rights_inheriting,
+    __wasi_fdflags_t fdflags,
+    __wasi_fdflagsext_t fdflagsext,
+    __wasi_fd_t *retptr0
+) __attribute__((__warn_unused_result__));
+/**
+ * Get the FD flags of a file descriptor (fdflagsext).
+ * Note: This returns similar flags to `fsync(fd, F_GETFD)` in POSIX.
+ * @return
+ * The buffer where the file descriptor's attributes are stored.
+ */
+__wasi_errno_t __wasi_fd_fdflags_get(
+    __wasi_fd_t fd,
+    __wasi_fdflagsext_t *retptr0
+) __attribute__((__warn_unused_result__));
+/**
+ * Adjust the FD flags associated with a file descriptor.
+ * Note: This is similar to `fcntl(fd, F_SETFD, flags)` in POSIX.
+ */
+__wasi_errno_t __wasi_fd_fdflags_set(
+    __wasi_fd_t fd,
+    /**
+     * The desired values of the file descriptor flags.
+     */
+    __wasi_fdflagsext_t flags
+) __attribute__((__warn_unused_result__));
 /**
  * Send a signal to the process of the calling thread on a regular basis
  * Note: This is similar to `setitimer` in POSIX.
diff --git a/libc-bottom-half/sources/__wasixlibc_real.c b/libc-bottom-half/sources/__wasixlibc_real.c
index 5c265a80c..20b986312 100644
--- a/libc-bottom-half/sources/__wasixlibc_real.c
+++ b/libc-bottom-half/sources/__wasixlibc_real.c
@@ -39,6 +39,21 @@ __wasi_errno_t __wasi_fd_dup(
     return (uint16_t) ret;
 }
 
+int32_t __imported_wasix_32v1_fd_dup2(int32_t arg0, int32_t arg1, int32_t arg2, int32_t arg3) __attribute__((
+    __import_module__("wasix_32v1"),
+    __import_name__("fd_dup2")
+));
+
+__wasi_errno_t __wasi_fd_dup2(
+    __wasi_fd_t fd,
+    __wasi_fd_t min_result_fd,
+    __wasi_bool_t cloexec,
+    __wasi_fd_t *retptr0
+){
+    int32_t ret = __imported_wasix_32v1_fd_dup2((int32_t) fd, (int32_t) min_result_fd, (int32_t) cloexec, (intptr_t) retptr0);
+    return (uint16_t) ret;
+}
+
 int32_t __imported_wasix_32v1_fd_event(int64_t arg0, int32_t arg1, int32_t arg2) __attribute__((
     __import_module__("wasix_32v1"),
     __import_name__("fd_event")
@@ -279,6 +294,53 @@ _Noreturn void __wasi_stack_restore(
     __imported_wasix_32v1_stack_restore((int32_t) snapshot, (int64_t) val);
 }
 
+int32_t __imported_wasix_32v1_path_open2(int32_t arg0, int32_t arg1, int32_t arg2, int32_t arg3, int32_t arg4, int64_t arg5, int64_t arg6, int32_t arg7, int32_t arg8, int32_t arg9) __attribute__((
+    __import_module__("wasix_32v1"),
+    __import_name__("path_open2")
+));
+
+__wasi_errno_t __wasi_path_open2(
+    __wasi_fd_t fd,
+    __wasi_lookupflags_t dirflags,
+    const char *path,
+    __wasi_oflags_t oflags,
+    __wasi_rights_t fs_rights_base,
+    __wasi_rights_t fs_rights_inheriting,
+    __wasi_fdflags_t fdflags,
+    __wasi_fdflagsext_t fdflagsext,
+    __wasi_fd_t *retptr0
+){
+    size_t path_len = strlen(path);
+    int32_t ret = __imported_wasix_32v1_path_open2((int32_t) fd, dirflags, (intptr_t) path, (intptr_t) path_len, oflags, fs_rights_base, fs_rights_inheriting, fdflags, fdflagsext, (intptr_t) retptr0);
+    return (uint16_t) ret;
+}
+
+int32_t __imported_wasix_32v1_fd_fdflags_get(int32_t arg0, int32_t arg1) __attribute__((
+    __import_module__("wasix_32v1"),
+    __import_name__("fd_fdflags_get")
+));
+
+__wasi_errno_t __wasi_fd_fdflags_get(
+    __wasi_fd_t fd,
+    __wasi_fdflagsext_t *retptr0
+){
+    int32_t ret = __imported_wasix_32v1_fd_fdflags_get((int32_t) fd, (intptr_t) retptr0);
+    return (uint16_t) ret;
+}
+
+int32_t __imported_wasix_32v1_fd_fdflags_set(int32_t arg0, int32_t arg1) __attribute__((
+    __import_module__("wasix_32v1"),
+    __import_name__("fd_fdflags_set")
+));
+
+__wasi_errno_t __wasi_fd_fdflags_set(
+    __wasi_fd_t fd,
+    __wasi_fdflagsext_t flags
+){
+    int32_t ret = __imported_wasix_32v1_fd_fdflags_set((int32_t) fd, flags);
+    return (uint16_t) ret;
+}
+
 int32_t __imported_wasix_32v1_proc_raise_interval(int32_t arg0, int64_t arg1, int32_t arg2) __attribute__((
     __import_module__("wasix_32v1"),
     __import_name__("proc_raise_interval")
diff --git a/libc-top-half/musl/src/thread/thrd_create.c b/libc-top-half/musl/src/thread/thrd_create.c
index 76a683dbf..d6f787934 100644
--- a/libc-top-half/musl/src/thread/thrd_create.c
+++ b/libc-top-half/musl/src/thread/thrd_create.c
@@ -3,7 +3,7 @@
 
 int thrd_create(thrd_t *thr, thrd_start_t func, void *arg)
 {
-	int ret = __pthread_create(thr, __ATTRP_C11_THREAD, (void *(*)(void *))func, arg);
+	int ret = __pthread_create(thr, __ATTRP_C11_THREAD, (void *(*)(void *))(void *)func, arg);
 	switch (ret) {
 	case 0:      return thrd_success;
 	case EAGAIN: return thrd_nomem;