diff --git a/library/alloc/src/collections/binary_heap.rs b/library/alloc/src/collections/binary_heap.rs
index 28e4f8bba05c8..d228c66f52492 100644
--- a/library/alloc/src/collections/binary_heap.rs
+++ b/library/alloc/src/collections/binary_heap.rs
@@ -506,6 +506,10 @@ impl<T: Ord> BinaryHeap<T> {
     /// let vec = heap.into_sorted_vec();
     /// assert_eq!(vec, [1, 2, 3, 4, 5, 6, 7]);
     /// ```
+    ///
+    /// # Time complexity
+    ///
+    /// The time complexity of `into_sorted_vec` on a heap containing `n` items is *O*(*n*log(*n*)).
     #[stable(feature = "binary_heap_extras_15", since = "1.5.0")]
     pub fn into_sorted_vec(mut self) -> Vec<T> {
         let mut end = self.len();
diff --git a/library/alloc/src/collections/linked_list.rs b/library/alloc/src/collections/linked_list.rs
index 9d45c5082db43..c5c32674eec15 100644
--- a/library/alloc/src/collections/linked_list.rs
+++ b/library/alloc/src/collections/linked_list.rs
@@ -631,6 +631,8 @@ impl<T> LinkedList<T> {
     /// Returns `true` if the `LinkedList` contains an element equal to the
     /// given value.
     ///
+    /// This operation should compute in *O*(*n*) time.
+    ///
     /// # Examples
     ///
     /// ```
@@ -656,6 +658,8 @@ impl<T> LinkedList<T> {
     /// Provides a reference to the front element, or `None` if the list is
     /// empty.
     ///
+    /// This operation should compute in *O*(1) time.
+    ///
     /// # Examples
     ///
     /// ```
@@ -676,6 +680,8 @@ impl<T> LinkedList<T> {
     /// Provides a mutable reference to the front element, or `None` if the list
     /// is empty.
     ///
+    /// This operation should compute in *O*(1) time.
+    ///
     /// # Examples
     ///
     /// ```
@@ -702,6 +708,8 @@ impl<T> LinkedList<T> {
     /// Provides a reference to the back element, or `None` if the list is
     /// empty.
     ///
+    /// This operation should compute in *O*(1) time.
+    ///
     /// # Examples
     ///
     /// ```
@@ -722,6 +730,8 @@ impl<T> LinkedList<T> {
     /// Provides a mutable reference to the back element, or `None` if the list
     /// is empty.
     ///
+    /// This operation should compute in *O*(1) time.
+    ///
     /// # Examples
     ///
     /// ```