diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index caaf37f0465..38b1766c174 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -262,8 +262,6 @@ pub fn new(x: T) -> Self {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
-    ///
     /// let mut five = Box::<u32>::new_uninit();
     ///
     /// let five = unsafe {
@@ -276,7 +274,7 @@ pub fn new(x: T) -> Self {
     /// assert_eq!(*five, 5)
     /// ```
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub fn new_uninit() -> Box<mem::MaybeUninit<T>> {
@@ -292,7 +290,6 @@ pub fn new_uninit() -> Box<mem::MaybeUninit<T>> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(new_zeroed_alloc)]
     ///
     /// let zero = Box::<u32>::new_zeroed();
@@ -350,7 +347,7 @@ pub fn try_new(x: T) -> Result<Self, AllocError> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// let mut five = Box::<u32>::try_new_uninit()?;
     ///
@@ -380,7 +377,7 @@ pub fn try_new_uninit() -> Result<Box<mem::MaybeUninit<T>>, AllocError> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// let zero = Box::<u32>::try_new_zeroed()?;
     /// let zero = unsafe { zero.assume_init() };
@@ -460,7 +457,7 @@ pub fn try_new_in(x: T, alloc: A) -> Result<Self, AllocError>
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
@@ -498,7 +495,7 @@ pub fn new_uninit_in(alloc: A) -> Box<mem::MaybeUninit<T>, A>
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
@@ -538,7 +535,7 @@ pub fn try_new_uninit_in(alloc: A) -> Result<Box<mem::MaybeUninit<T>, A>, AllocE
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
@@ -576,7 +573,7 @@ pub fn new_zeroed_in(alloc: A) -> Box<mem::MaybeUninit<T>, A>
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
@@ -654,8 +651,6 @@ impl<T> Box<[T]> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
-    ///
     /// let mut values = Box::<[u32]>::new_uninit_slice(3);
     ///
     /// let values = unsafe {
@@ -670,7 +665,7 @@ impl<T> Box<[T]> {
     /// assert_eq!(*values, [1, 2, 3])
     /// ```
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_uninit_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {
         unsafe { RawVec::with_capacity(len).into_box(len) }
@@ -686,7 +681,6 @@ pub fn new_uninit_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {
     ///
     /// ```
     /// #![feature(new_zeroed_alloc)]
-    /// #![feature(new_uninit)]
     ///
     /// let values = Box::<[u32]>::new_zeroed_slice(3);
     /// let values = unsafe { values.assume_init() };
@@ -708,7 +702,7 @@ pub fn new_zeroed_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// let mut values = Box::<[u32]>::try_new_uninit_slice(3)?;
     /// let values = unsafe {
@@ -746,7 +740,7 @@ pub fn try_new_uninit_slice(len: usize) -> Result<Box<[mem::MaybeUninit<T>]>, Al
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// let values = Box::<[u32]>::try_new_zeroed_slice(3)?;
     /// let values = unsafe { values.assume_init() };
@@ -778,7 +772,7 @@ impl<T, A: Allocator> Box<[T], A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
@@ -812,7 +806,7 @@ pub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
@@ -837,7 +831,7 @@ pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
@@ -880,7 +874,7 @@ pub fn try_new_uninit_slice_in(
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
@@ -927,8 +921,6 @@ impl<T, A: Allocator> Box<mem::MaybeUninit<T>, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
-    ///
     /// let mut five = Box::<u32>::new_uninit();
     ///
     /// let five: Box<u32> = unsafe {
@@ -940,7 +932,7 @@ impl<T, A: Allocator> Box<mem::MaybeUninit<T>, A> {
     ///
     /// assert_eq!(*five, 5)
     /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub unsafe fn assume_init(self) -> Box<T, A> {
         let (raw, alloc) = Box::into_raw_with_allocator(self);
@@ -958,7 +950,6 @@ pub unsafe fn assume_init(self) -> Box<T, A> {
     ///
     /// ```
     /// #![feature(box_uninit_write)]
-    /// #![feature(new_uninit)]
     ///
     /// let big_box = Box::<[usize; 1024]>::new_uninit();
     ///
@@ -1001,8 +992,6 @@ impl<T, A: Allocator> Box<[mem::MaybeUninit<T>], A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
-    ///
     /// let mut values = Box::<[u32]>::new_uninit_slice(3);
     ///
     /// let values = unsafe {
@@ -1016,7 +1005,7 @@ impl<T, A: Allocator> Box<[mem::MaybeUninit<T>], A> {
     ///
     /// assert_eq!(*values, [1, 2, 3])
     /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub unsafe fn assume_init(self) -> Box<[T], A> {
         let (raw, alloc) = Box::into_raw_with_allocator(self);
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 5e4b08df6cb..c459a8da820 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -93,7 +93,6 @@
 // tidy-alphabetical-start
 #![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))]
 #![cfg_attr(not(no_global_oom_handling), feature(const_btree_len))]
-#![cfg_attr(test, feature(new_uninit))]
 #![feature(alloc_layout_extra)]
 #![feature(allocator_api)]
 #![feature(array_chunks)]
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index f153aa6d3be..1b31a78394e 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -503,7 +503,6 @@ pub fn new_cyclic<F>(data_fn: F) -> Rc<T>
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::rc::Rc;
@@ -518,7 +517,7 @@ pub fn new_cyclic<F>(data_fn: F) -> Rc<T>
     /// assert_eq!(*five, 5)
     /// ```
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_uninit() -> Rc<mem::MaybeUninit<T>> {
         unsafe {
@@ -540,7 +539,6 @@ pub fn new_uninit() -> Rc<mem::MaybeUninit<T>> {
     ///
     /// ```
     /// #![feature(new_zeroed_alloc)]
-    /// #![feature(new_uninit)]
     ///
     /// use std::rc::Rc;
     ///
@@ -594,7 +592,7 @@ pub fn try_new(value: T) -> Result<Rc<T>, AllocError> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::rc::Rc;
@@ -630,7 +628,7 @@ pub fn try_new_uninit() -> Result<Rc<mem::MaybeUninit<T>>, AllocError> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::rc::Rc;
     ///
@@ -692,7 +690,6 @@ pub fn new_in(value: T, alloc: A) -> Rc<T, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     /// #![feature(allocator_api)]
     ///
@@ -736,7 +733,6 @@ pub fn new_uninit_in(alloc: A) -> Rc<mem::MaybeUninit<T>, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(allocator_api)]
     ///
     /// use std::rc::Rc;
@@ -799,7 +795,7 @@ pub fn try_new_in(value: T, alloc: A) -> Result<Self, AllocError> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::rc::Rc;
@@ -843,7 +839,7 @@ pub fn try_new_uninit_in(alloc: A) -> Result<Rc<mem::MaybeUninit<T>, A>, AllocEr
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, new_uninit)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::rc::Rc;
     /// use std::alloc::System;
@@ -967,7 +963,6 @@ impl<T> Rc<[T]> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::rc::Rc;
@@ -985,7 +980,7 @@ impl<T> Rc<[T]> {
     /// assert_eq!(*values, [1, 2, 3])
     /// ```
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_uninit_slice(len: usize) -> Rc<[mem::MaybeUninit<T>]> {
         unsafe { Rc::from_ptr(Rc::allocate_for_slice(len)) }
@@ -1000,7 +995,6 @@ pub fn new_uninit_slice(len: usize) -> Rc<[mem::MaybeUninit<T>]> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(new_zeroed_alloc)]
     ///
     /// use std::rc::Rc;
@@ -1035,7 +1029,6 @@ impl<T, A: Allocator> Rc<[T], A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     /// #![feature(allocator_api)]
     ///
@@ -1072,7 +1065,6 @@ pub fn new_uninit_slice_in(len: usize, alloc: A) -> Rc<[mem::MaybeUninit<T>], A>
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(allocator_api)]
     ///
     /// use std::rc::Rc;
@@ -1122,7 +1114,6 @@ impl<T, A: Allocator> Rc<mem::MaybeUninit<T>, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::rc::Rc;
@@ -1136,7 +1127,7 @@ impl<T, A: Allocator> Rc<mem::MaybeUninit<T>, A> {
     ///
     /// assert_eq!(*five, 5)
     /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub unsafe fn assume_init(self) -> Rc<T, A> {
         let (ptr, alloc) = Rc::into_inner_with_allocator(self);
@@ -1160,7 +1151,6 @@ impl<T, A: Allocator> Rc<[mem::MaybeUninit<T>], A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::rc::Rc;
@@ -1177,7 +1167,7 @@ impl<T, A: Allocator> Rc<[mem::MaybeUninit<T>], A> {
     ///
     /// assert_eq!(*values, [1, 2, 3])
     /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub unsafe fn assume_init(self) -> Rc<[T], A> {
         let (ptr, alloc) = Rc::into_inner_with_allocator(self);
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index 4a3522f1a64..aac768eb053 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -505,7 +505,6 @@ pub fn new_cyclic<F>(data_fn: F) -> Arc<T>
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::sync::Arc;
@@ -521,7 +520,7 @@ pub fn new_cyclic<F>(data_fn: F) -> Arc<T>
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[inline]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_uninit() -> Arc<mem::MaybeUninit<T>> {
         unsafe {
@@ -543,7 +542,6 @@ pub fn new_uninit() -> Arc<mem::MaybeUninit<T>> {
     ///
     /// ```
     /// #![feature(new_zeroed_alloc)]
-    /// #![feature(new_uninit)]
     ///
     /// use std::sync::Arc;
     ///
@@ -614,7 +612,7 @@ pub fn try_new(data: T) -> Result<Arc<T>, AllocError> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit, allocator_api)]
+    /// #![feature(allocator_api)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::sync::Arc;
@@ -650,7 +648,7 @@ pub fn try_new_uninit() -> Result<Arc<mem::MaybeUninit<T>>, AllocError> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit, allocator_api)]
+    /// #![feature( allocator_api)]
     ///
     /// use std::sync::Arc;
     ///
@@ -711,7 +709,6 @@ pub fn new_in(data: T, alloc: A) -> Arc<T, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     /// #![feature(allocator_api)]
     ///
@@ -755,7 +752,6 @@ pub fn new_uninit_in(alloc: A) -> Arc<mem::MaybeUninit<T>, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(allocator_api)]
     ///
     /// use std::sync::Arc;
@@ -845,7 +841,7 @@ pub fn try_new_in(data: T, alloc: A) -> Result<Arc<T, A>, AllocError> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit, allocator_api)]
+    /// #![feature(allocator_api)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::sync::Arc;
@@ -889,7 +885,7 @@ pub fn try_new_uninit_in(alloc: A) -> Result<Arc<mem::MaybeUninit<T>, A>, AllocE
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit, allocator_api)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::sync::Arc;
     /// use std::alloc::System;
@@ -1101,7 +1097,6 @@ impl<T> Arc<[T]> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::sync::Arc;
@@ -1120,7 +1115,7 @@ impl<T> Arc<[T]> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[inline]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_uninit_slice(len: usize) -> Arc<[mem::MaybeUninit<T>]> {
         unsafe { Arc::from_ptr(Arc::allocate_for_slice(len)) }
@@ -1136,7 +1131,6 @@ pub fn new_uninit_slice(len: usize) -> Arc<[mem::MaybeUninit<T>]> {
     ///
     /// ```
     /// #![feature(new_zeroed_alloc)]
-    /// #![feature(new_uninit)]
     ///
     /// use std::sync::Arc;
     ///
@@ -1172,7 +1166,6 @@ impl<T, A: Allocator> Arc<[T], A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     /// #![feature(allocator_api)]
     ///
@@ -1208,7 +1201,6 @@ pub fn new_uninit_slice_in(len: usize, alloc: A) -> Arc<[mem::MaybeUninit<T>], A
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(allocator_api)]
     ///
     /// use std::sync::Arc;
@@ -1257,7 +1249,6 @@ impl<T, A: Allocator> Arc<mem::MaybeUninit<T>, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::sync::Arc;
@@ -1271,7 +1262,7 @@ impl<T, A: Allocator> Arc<mem::MaybeUninit<T>, A> {
     ///
     /// assert_eq!(*five, 5)
     /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[must_use = "`self` will be dropped if the result is not used"]
     #[inline]
     pub unsafe fn assume_init(self) -> Arc<T, A> {
@@ -1296,7 +1287,6 @@ impl<T, A: Allocator> Arc<[mem::MaybeUninit<T>], A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_uninit)]
     /// #![feature(get_mut_unchecked)]
     ///
     /// use std::sync::Arc;
@@ -1313,7 +1303,7 @@ impl<T, A: Allocator> Arc<[mem::MaybeUninit<T>], A> {
     ///
     /// assert_eq!(*values, [1, 2, 3])
     /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[stable(feature = "new_uninit", since = "CURRENT_RUSTC_VERSION")]
     #[must_use = "`self` will be dropped if the result is not used"]
     #[inline]
     pub unsafe fn assume_init(self) -> Arc<[T], A> {
diff --git a/library/alloc/tests/lib.rs b/library/alloc/tests/lib.rs
index 3d4add6fae4..c5c6a122cfe 100644
--- a/library/alloc/tests/lib.rs
+++ b/library/alloc/tests/lib.rs
@@ -15,7 +15,6 @@
 #![feature(exact_size_is_empty)]
 #![feature(linked_list_cursors)]
 #![feature(map_try_insert)]
-#![feature(new_uninit)]
 #![feature(pattern)]
 #![feature(trusted_len)]
 #![feature(try_reserve_kind)]
diff --git a/library/proc_macro/src/lib.rs b/library/proc_macro/src/lib.rs
index c271ac18706..72b53c60f74 100644
--- a/library/proc_macro/src/lib.rs
+++ b/library/proc_macro/src/lib.rs
@@ -28,7 +28,6 @@
 #![feature(decl_macro)]
 #![feature(maybe_uninit_write_slice)]
 #![feature(negative_impls)]
-#![feature(new_uninit)]
 #![feature(panic_can_unwind)]
 #![feature(restricted_std)]
 #![feature(rustc_attrs)]
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index f65e9bc8d8b..bea8eda2619 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -362,7 +362,6 @@
 #![feature(allocator_api)]
 #![feature(get_mut_unchecked)]
 #![feature(map_try_insert)]
-#![feature(new_uninit)]
 #![feature(new_zeroed_alloc)]
 #![feature(slice_concat_trait)]
 #![feature(thin_box)]