diff --git a/src/libcollections/string.rs b/src/libcollections/string.rs
index 7a61451b900c0..ce9fec3291724 100644
--- a/src/libcollections/string.rs
+++ b/src/libcollections/string.rs
@@ -1860,6 +1860,13 @@ impl<'a> From<&'a str> for String {
     }
 }
 
+#[stable(feature = "string_from_cow_str", since = "1.14.0")]
+impl<'a> From<Cow<'a, str>> for String {
+    fn from(s: Cow<'a, str>) -> String {
+        s.into_owned()
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> From<&'a str> for Cow<'a, str> {
     #[inline]
diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index f3d78c20a4d6b..f7c3e8ea1ede4 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -1764,6 +1764,13 @@ impl<'a, T: Clone> From<&'a [T]> for Vec<T> {
     }
 }
 
+#[stable(feature = "vec_from_cow_slice", since = "1.14.0")]
+impl<'a, T> From<Cow<'a, [T]>> for Vec<T> where [T]: ToOwned<Owned=Vec<T>> {
+    fn from(s: Cow<'a, [T]>) -> Vec<T> {
+        s.into_owned()
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> From<&'a str> for Vec<u8> {
     fn from(s: &'a str) -> Vec<u8> {
diff --git a/src/libcollectionstest/string.rs b/src/libcollectionstest/string.rs
index 1652fb5a88d80..98de33bdaa8e1 100644
--- a/src/libcollectionstest/string.rs
+++ b/src/libcollectionstest/string.rs
@@ -35,6 +35,12 @@ fn test_from_str() {
     assert_eq!(owned.as_ref().map(|s| &**s), Some("string"));
 }
 
+#[test]
+fn test_from_cow_str() {
+    assert_eq!(String::from(Cow::Borrowed("string")), "string");
+    assert_eq!(String::from(Cow::Owned(String::from("string"))), "string");
+}
+
 #[test]
 fn test_unsized_to_string() {
     let s: &str = "abc";
diff --git a/src/libcollectionstest/vec.rs b/src/libcollectionstest/vec.rs
index 991c456fe7463..9a04673d1da0d 100644
--- a/src/libcollectionstest/vec.rs
+++ b/src/libcollectionstest/vec.rs
@@ -597,6 +597,14 @@ fn test_cow_from() {
     }
 }
 
+#[test]
+fn test_from_cow() {
+    let borrowed: &[_] = &["borrowed", "(slice)"];
+    let owned = vec!["owned", "(vec)"];
+    assert_eq!(Vec::from(Cow::Borrowed(borrowed)), vec!["borrowed", "(slice)"]);
+    assert_eq!(Vec::from(Cow::Owned(owned)), vec!["owned", "(vec)"]);
+}
+
 #[allow(dead_code)]
 fn assert_covariance() {
     fn drain<'new>(d: Drain<'static, &'static str>) -> Drain<'new, &'new str> { d }