diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 76dabfb429dd5..e9cc3875f683b 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -116,7 +116,6 @@
 #![feature(const_eval_select)]
 #![feature(const_pin)]
 #![feature(const_waker)]
-#![feature(cstr_from_bytes_until_nul)]
 #![feature(dispatch_from_dyn)]
 #![feature(error_generic_member_access)]
 #![feature(error_in_core)]
diff --git a/library/core/src/error.rs b/library/core/src/error.rs
index d2fac23ff18be..e11a5e99184cb 100644
--- a/library/core/src/error.rs
+++ b/library/core/src/error.rs
@@ -505,7 +505,7 @@ impl Error for crate::ffi::FromBytesWithNulError {
     }
 }
 
-#[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")]
+#[stable(feature = "cstr_from_bytes_until_nul", since = "CURRENT_RUSTC_VERSION")]
 impl Error for crate::ffi::FromBytesUntilNulError {}
 
 #[unstable(feature = "get_many_mut", issue = "104642")]
diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index 15dd9ea7e8036..82e5fa75ded84 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -150,10 +150,10 @@ impl FromBytesWithNulError {
 /// This error is created by the [`CStr::from_bytes_until_nul`] method.
 ///
 #[derive(Clone, PartialEq, Eq, Debug)]
-#[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")]
+#[stable(feature = "cstr_from_bytes_until_nul", since = "CURRENT_RUSTC_VERSION")]
 pub struct FromBytesUntilNulError(());
 
-#[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")]
+#[stable(feature = "cstr_from_bytes_until_nul", since = "CURRENT_RUSTC_VERSION")]
 impl fmt::Display for FromBytesUntilNulError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "data provided does not contain a nul")
@@ -306,8 +306,6 @@ impl CStr {
     ///
     /// # Examples
     /// ```
-    /// #![feature(cstr_from_bytes_until_nul)]
-    ///
     /// use std::ffi::CStr;
     ///
     /// let mut buffer = [0u8; 16];
@@ -322,8 +320,9 @@ impl CStr {
     /// assert_eq!(c_str.to_str().unwrap(), "AAAAAAAA");
     /// ```
     ///
-    #[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")]
-    #[rustc_const_unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")]
+    #[rustc_allow_const_fn_unstable(const_slice_index)]
+    #[stable(feature = "cstr_from_bytes_until_nul", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "cstr_from_bytes_until_nul", since = "CURRENT_RUSTC_VERSION")]
     pub const fn from_bytes_until_nul(bytes: &[u8]) -> Result<&CStr, FromBytesUntilNulError> {
         let nul_pos = memchr::memchr(0, bytes);
         match nul_pos {
diff --git a/library/core/src/slice/memchr.rs b/library/core/src/slice/memchr.rs
index c848c2e18e9b5..98c8349eb6024 100644
--- a/library/core/src/slice/memchr.rs
+++ b/library/core/src/slice/memchr.rs
@@ -16,25 +16,29 @@ const USIZE_BYTES: usize = mem::size_of::<usize>();
 /// bytes where the borrow propagated all the way to the most significant
 /// bit."
 #[inline]
+#[rustc_const_stable(feature = "const_memchr", since = "1.65.0")]
 const fn contains_zero_byte(x: usize) -> bool {
     x.wrapping_sub(LO_USIZE) & !x & HI_USIZE != 0
 }
 
-#[cfg(target_pointer_width = "16")]
 #[inline]
+#[cfg(target_pointer_width = "16")]
+#[rustc_const_stable(feature = "const_memchr", since = "1.65.0")]
 const fn repeat_byte(b: u8) -> usize {
     (b as usize) << 8 | b as usize
 }
 
-#[cfg(not(target_pointer_width = "16"))]
 #[inline]
+#[cfg(not(target_pointer_width = "16"))]
+#[rustc_const_stable(feature = "const_memchr", since = "1.65.0")]
 const fn repeat_byte(b: u8) -> usize {
     (b as usize) * (usize::MAX / 255)
 }
 
 /// Returns the first index matching the byte `x` in `text`.
-#[must_use]
 #[inline]
+#[must_use]
+#[rustc_const_stable(feature = "const_memchr", since = "1.65.0")]
 pub const fn memchr(x: u8, text: &[u8]) -> Option<usize> {
     // Fast path for small slices.
     if text.len() < 2 * USIZE_BYTES {
@@ -45,6 +49,7 @@ pub const fn memchr(x: u8, text: &[u8]) -> Option<usize> {
 }
 
 #[inline]
+#[rustc_const_stable(feature = "const_memchr", since = "1.65.0")]
 const fn memchr_naive(x: u8, text: &[u8]) -> Option<usize> {
     let mut i = 0;
 
@@ -60,6 +65,10 @@ const fn memchr_naive(x: u8, text: &[u8]) -> Option<usize> {
     None
 }
 
+#[rustc_allow_const_fn_unstable(const_cmp)]
+#[rustc_allow_const_fn_unstable(const_slice_index)]
+#[rustc_allow_const_fn_unstable(const_align_offset)]
+#[rustc_const_stable(feature = "const_memchr", since = "1.65.0")]
 const fn memchr_aligned(x: u8, text: &[u8]) -> Option<usize> {
     // Scan for a single byte value by reading two `usize` words at a time.
     //
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 762f7a7c9a1a0..cd9f74820ae9b 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -278,7 +278,6 @@
 #![feature(char_error_internals)]
 #![feature(char_internals)]
 #![feature(core_intrinsics)]
-#![feature(cstr_from_bytes_until_nul)]
 #![feature(cstr_internals)]
 #![feature(duration_constants)]
 #![feature(error_generic_member_access)]
diff --git a/src/tools/miri/tests/pass-dep/shims/pthreads.rs b/src/tools/miri/tests/pass-dep/shims/pthreads.rs
index 09dd92564d39a..80b8d67401ad1 100644
--- a/src/tools/miri/tests/pass-dep/shims/pthreads.rs
+++ b/src/tools/miri/tests/pass-dep/shims/pthreads.rs
@@ -1,5 +1,4 @@
 //@ignore-target-windows: No libc on Windows
-#![feature(cstr_from_bytes_until_nul)]
 use std::ffi::{CStr, CString};
 use std::thread;