diff --git a/library/alloc/tests/lib.rs b/library/alloc/tests/lib.rs
index cd4174ed4007a..0b7eeab4e9679 100644
--- a/library/alloc/tests/lib.rs
+++ b/library/alloc/tests/lib.rs
@@ -14,7 +14,6 @@
 #![feature(binary_heap_into_iter_sorted)]
 #![feature(binary_heap_drain_sorted)]
 #![feature(slice_ptr_get)]
-#![feature(split_inclusive)]
 #![feature(binary_heap_retain)]
 #![feature(inplace_iteration)]
 #![feature(iter_map_while)]
diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index 769b673d80ab5..50664267a6755 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -446,15 +446,13 @@ impl<T, P> FusedIterator for Split<'_, T, P> where P: FnMut(&T) -> bool {}
 /// # Example
 ///
 /// ```
-/// #![feature(split_inclusive)]
-///
 /// let slice = [10, 40, 33, 20];
 /// let mut iter = slice.split_inclusive(|num| num % 3 == 0);
 /// ```
 ///
 /// [`split_inclusive`]: ../../std/primitive.slice.html#method.split_inclusive
 /// [slices]: ../../std/primitive.slice.html
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 pub struct SplitInclusive<'a, T: 'a, P>
 where
     P: FnMut(&T) -> bool,
@@ -471,7 +469,7 @@ impl<'a, T: 'a, P: FnMut(&T) -> bool> SplitInclusive<'a, T, P> {
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<T: fmt::Debug, P> fmt::Debug for SplitInclusive<'_, T, P>
 where
     P: FnMut(&T) -> bool,
@@ -485,7 +483,7 @@ where
 }
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<T, P> Clone for SplitInclusive<'_, T, P>
 where
     P: Clone + FnMut(&T) -> bool,
@@ -495,7 +493,7 @@ where
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, T, P> Iterator for SplitInclusive<'a, T, P>
 where
     P: FnMut(&T) -> bool,
@@ -524,7 +522,7 @@ where
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, T, P> DoubleEndedIterator for SplitInclusive<'a, T, P>
 where
     P: FnMut(&T) -> bool,
@@ -549,7 +547,7 @@ where
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<T, P> FusedIterator for SplitInclusive<'_, T, P> where P: FnMut(&T) -> bool {}
 
 /// An iterator over the mutable subslices of the vector which are separated
@@ -689,15 +687,13 @@ impl<T, P> FusedIterator for SplitMut<'_, T, P> where P: FnMut(&T) -> bool {}
 /// # Example
 ///
 /// ```
-/// #![feature(split_inclusive)]
-///
 /// let mut v = [10, 40, 30, 20, 60, 50];
 /// let iter = v.split_inclusive_mut(|num| *num % 3 == 0);
 /// ```
 ///
 /// [`split_inclusive_mut`]: ../../std/primitive.slice.html#method.split_inclusive_mut
 /// [slices]: ../../std/primitive.slice.html
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 pub struct SplitInclusiveMut<'a, T: 'a, P>
 where
     P: FnMut(&T) -> bool,
@@ -714,7 +710,7 @@ impl<'a, T: 'a, P: FnMut(&T) -> bool> SplitInclusiveMut<'a, T, P> {
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<T: fmt::Debug, P> fmt::Debug for SplitInclusiveMut<'_, T, P>
 where
     P: FnMut(&T) -> bool,
@@ -727,7 +723,7 @@ where
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, T, P> Iterator for SplitInclusiveMut<'a, T, P>
 where
     P: FnMut(&T) -> bool,
@@ -767,7 +763,7 @@ where
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, T, P> DoubleEndedIterator for SplitInclusiveMut<'a, T, P>
 where
     P: FnMut(&T) -> bool,
@@ -801,7 +797,7 @@ where
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<T, P> FusedIterator for SplitInclusiveMut<'_, T, P> where P: FnMut(&T) -> bool {}
 
 /// An iterator over subslices separated by elements that match a predicate
diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index 439a39b8276a2..081d80f487605 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -60,7 +60,7 @@ pub use iter::ArrayWindows;
 #[unstable(feature = "slice_group_by", issue = "80552")]
 pub use iter::{GroupBy, GroupByMut};
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 pub use iter::{SplitInclusive, SplitInclusiveMut};
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1546,7 +1546,6 @@ impl<T> [T] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(split_inclusive)]
     /// let slice = [10, 40, 33, 20];
     /// let mut iter = slice.split_inclusive(|num| num % 3 == 0);
     ///
@@ -1560,7 +1559,6 @@ impl<T> [T] {
     /// That slice will be the last item returned by the iterator.
     ///
     /// ```
-    /// #![feature(split_inclusive)]
     /// let slice = [3, 10, 40, 33];
     /// let mut iter = slice.split_inclusive(|num| num % 3 == 0);
     ///
@@ -1568,7 +1566,7 @@ impl<T> [T] {
     /// assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
     /// assert!(iter.next().is_none());
     /// ```
-    #[unstable(feature = "split_inclusive", issue = "72360")]
+    #[stable(feature = "split_inclusive", since = "1.51.0")]
     #[inline]
     pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F>
     where
@@ -1584,7 +1582,6 @@ impl<T> [T] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(split_inclusive)]
     /// let mut v = [10, 40, 30, 20, 60, 50];
     ///
     /// for group in v.split_inclusive_mut(|num| *num % 3 == 0) {
@@ -1593,7 +1590,7 @@ impl<T> [T] {
     /// }
     /// assert_eq!(v, [10, 40, 1, 20, 1, 1]);
     /// ```
-    #[unstable(feature = "split_inclusive", issue = "72360")]
+    #[stable(feature = "split_inclusive", since = "1.51.0")]
     #[inline]
     pub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F>
     where
diff --git a/library/core/src/str/iter.rs b/library/core/src/str/iter.rs
index 28cd350019ebf..8b952eab2946d 100644
--- a/library/core/src/str/iter.rs
+++ b/library/core/src/str/iter.rs
@@ -1174,7 +1174,7 @@ pub struct SplitAsciiWhitespace<'a> {
 /// See its documentation for more.
 ///
 /// [`split_inclusive`]: str::split_inclusive
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 pub struct SplitInclusive<'a, P: Pattern<'a>>(pub(super) SplitInternal<'a, P>);
 
 #[stable(feature = "split_whitespace", since = "1.1.0")]
@@ -1239,7 +1239,7 @@ impl<'a> DoubleEndedIterator for SplitAsciiWhitespace<'a> {
 #[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
 impl FusedIterator for SplitAsciiWhitespace<'_> {}
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, P: Pattern<'a>> Iterator for SplitInclusive<'a, P> {
     type Item = &'a str;
 
@@ -1249,7 +1249,7 @@ impl<'a, P: Pattern<'a>> Iterator for SplitInclusive<'a, P> {
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, P: Pattern<'a, Searcher: fmt::Debug>> fmt::Debug for SplitInclusive<'a, P> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("SplitInclusive").field("0", &self.0).finish()
@@ -1257,14 +1257,14 @@ impl<'a, P: Pattern<'a, Searcher: fmt::Debug>> fmt::Debug for SplitInclusive<'a,
 }
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, P: Pattern<'a, Searcher: Clone>> Clone for SplitInclusive<'a, P> {
     fn clone(&self) -> Self {
         SplitInclusive(self.0.clone())
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, P: Pattern<'a, Searcher: ReverseSearcher<'a>>> DoubleEndedIterator
     for SplitInclusive<'a, P>
 {
@@ -1274,7 +1274,7 @@ impl<'a, P: Pattern<'a, Searcher: ReverseSearcher<'a>>> DoubleEndedIterator
     }
 }
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, P: Pattern<'a>> FusedIterator for SplitInclusive<'a, P> {}
 
 impl<'a, P: Pattern<'a>> SplitInclusive<'a, P> {
@@ -1284,7 +1284,6 @@ impl<'a, P: Pattern<'a>> SplitInclusive<'a, P> {
     ///
     /// ```
     /// #![feature(str_split_inclusive_as_str)]
-    /// #![feature(split_inclusive)]
     /// let mut split = "Mary had a little lamb".split_inclusive(' ');
     /// assert_eq!(split.as_str(), "Mary had a little lamb");
     /// split.next();
diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index ae7892291ed19..6a35378ca7b50 100644
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs
@@ -65,7 +65,7 @@ pub use iter::{EscapeDebug, EscapeDefault, EscapeUnicode};
 #[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
 pub use iter::SplitAsciiWhitespace;
 
-#[unstable(feature = "split_inclusive", issue = "72360")]
+#[stable(feature = "split_inclusive", since = "1.51.0")]
 use iter::SplitInclusive;
 
 #[unstable(feature = "str_internals", issue = "none")]
@@ -1227,7 +1227,6 @@ impl str {
     /// # Examples
     ///
     /// ```
-    /// #![feature(split_inclusive)]
     /// let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb."
     ///     .split_inclusive('\n').collect();
     /// assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb."]);
@@ -1238,12 +1237,11 @@ impl str {
     /// That substring will be the last item returned by the iterator.
     ///
     /// ```
-    /// #![feature(split_inclusive)]
     /// let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb.\n"
     ///     .split_inclusive('\n').collect();
     /// assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb.\n"]);
     /// ```
-    #[unstable(feature = "split_inclusive", issue = "72360")]
+    #[stable(feature = "split_inclusive", since = "1.51.0")]
     #[inline]
     pub fn split_inclusive<'a, P: Pattern<'a>>(&'a self, pat: P) -> SplitInclusive<'a, P> {
         SplitInclusive(SplitInternal {
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index efcb006870c5a..719aca612f50d 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -15,7 +15,6 @@
 #![feature(never_type)]
 #![feature(once_cell)]
 #![feature(type_ascription)]
-#![feature(split_inclusive)]
 #![feature(str_split_once)]
 #![feature(iter_intersperse)]
 #![recursion_limit = "256"]