diff --git a/library/std/src/lazy.rs b/library/std/src/lazy.rs
index 60eba96bcc0..bf801b3c8c7 100644
--- a/library/std/src/lazy.rs
+++ b/library/std/src/lazy.rs
@@ -516,6 +516,7 @@ mod tests {
             mpsc::channel,
             Mutex,
         },
+        thread,
     };
 
     #[test]
@@ -552,26 +553,8 @@ mod tests {
         }
     }
 
-    // miri doesn't support threads
-    #[cfg(not(miri))]
     fn spawn_and_wait<R: Send + 'static>(f: impl FnOnce() -> R + Send + 'static) -> R {
-        crate::thread::spawn(f).join().unwrap()
-    }
-
-    #[cfg(not(miri))]
-    fn spawn(f: impl FnOnce() + Send + 'static) {
-        let _ = crate::thread::spawn(f);
-    }
-
-    // "stub threads" for Miri
-    #[cfg(miri)]
-    fn spawn_and_wait<R: Send + 'static>(f: impl FnOnce() -> R + Send + 'static) -> R {
-        f(())
-    }
-
-    #[cfg(miri)]
-    fn spawn(f: impl FnOnce() + Send + 'static) {
-        f(())
+        thread::spawn(f).join().unwrap()
     }
 
     #[test]
@@ -734,7 +717,6 @@ mod tests {
     }
 
     #[test]
-    #[cfg_attr(miri, ignore)] // leaks memory
     fn static_sync_lazy() {
         static XS: SyncLazy<Vec<i32>> = SyncLazy::new(|| {
             let mut xs = Vec::new();
@@ -752,7 +734,6 @@ mod tests {
     }
 
     #[test]
-    #[cfg_attr(miri, ignore)] // leaks memory
     fn static_sync_lazy_via_fn() {
         fn xs() -> &'static Vec<i32> {
             static XS: SyncOnceCell<Vec<i32>> = SyncOnceCell::new();
@@ -811,7 +792,6 @@ mod tests {
     }
 
     #[test]
-    #[cfg_attr(miri, ignore)] // deadlocks without real threads
     fn sync_once_cell_does_not_leak_partially_constructed_boxes() {
         static ONCE_CELL: SyncOnceCell<String> = SyncOnceCell::new();
 
@@ -823,7 +803,7 @@ mod tests {
 
         for _ in 0..n_readers {
             let tx = tx.clone();
-            spawn(move || {
+            thread::spawn(move || {
                 loop {
                     if let Some(msg) = ONCE_CELL.get() {
                         tx.send(msg).unwrap();
@@ -835,7 +815,7 @@ mod tests {
             });
         }
         for _ in 0..n_writers {
-            spawn(move || {
+            thread::spawn(move || {
                 let _ = ONCE_CELL.set(MSG.to_owned());
             });
         }