diff --git a/src/libcollections/binary_heap.rs b/src/libcollections/binary_heap.rs
index 2f994e94ccc3..9f549fd72377 100644
--- a/src/libcollections/binary_heap.rs
+++ b/src/libcollections/binary_heap.rs
@@ -650,8 +650,8 @@ impl<'a, T: 'a> ExactSizeIterator for Drain<'a, T> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Ord> FromIterator<T> for BinaryHeap<T> {
-    fn from_iter<Iter: Iterator<Item=T>>(iter: Iter) -> BinaryHeap<T> {
-        BinaryHeap::from_vec(iter.collect())
+    fn from_iter<I: IntoIterator<Item=T>>(iter: I) -> BinaryHeap<T> {
+        BinaryHeap::from_vec(iter.into_iter().collect())
     }
 }
 
diff --git a/src/libcollections/bit.rs b/src/libcollections/bit.rs
index c1d79d820438..f4b65aab38b6 100644
--- a/src/libcollections/bit.rs
+++ b/src/libcollections/bit.rs
@@ -924,9 +924,9 @@ impl Default for BitVec {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl FromIterator<bool> for BitVec {
-    fn from_iter<I:Iterator<Item=bool>>(iterator: I) -> BitVec {
-        let mut ret = BitVec::new();
-        ret.extend(iterator);
+    fn from_iter<I: IntoIterator<Item=bool>>(iter: I) -> BitVec {
+        let mut ret = Bitv::new();
+        ret.extend(iter);
         ret
     }
 }
@@ -1134,9 +1134,9 @@ impl Default for BitSet {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl FromIterator<usize> for BitSet {
-    fn from_iter<I:Iterator<Item=usize>>(iterator: I) -> BitSet {
-        let mut ret = BitSet::new();
-        ret.extend(iterator);
+    fn from_iter<I: IntoIterator<Item=usize>>(iter: I) -> BitSet {
+        let mut ret = BitvSet::new();
+        ret.extend(iter);
         ret
     }
 }
diff --git a/src/libcollections/btree/map.rs b/src/libcollections/btree/map.rs
index 9273d50db856..262084d5a912 100644
--- a/src/libcollections/btree/map.rs
+++ b/src/libcollections/btree/map.rs
@@ -826,7 +826,7 @@ mod stack {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K: Ord, V> FromIterator<(K, V)> for BTreeMap<K, V> {
-    fn from_iter<T: Iterator<Item=(K, V)>>(iter: T) -> BTreeMap<K, V> {
+    fn from_iter<T: IntoIterator<Item=(K, V)>>(iter: T) -> BTreeMap<K, V> {
         let mut map = BTreeMap::new();
         map.extend(iter);
         map
diff --git a/src/libcollections/btree/set.rs b/src/libcollections/btree/set.rs
index d2241a674649..614971866231 100644
--- a/src/libcollections/btree/set.rs
+++ b/src/libcollections/btree/set.rs
@@ -473,7 +473,7 @@ impl<T: Ord> BTreeSet<T> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Ord> FromIterator<T> for BTreeSet<T> {
-    fn from_iter<Iter: Iterator<Item=T>>(iter: Iter) -> BTreeSet<T> {
+    fn from_iter<I: IntoIterator<Item=T>>(iter: I) -> BTreeSet<T> {
         let mut set = BTreeSet::new();
         set.extend(iter);
         set
diff --git a/src/libcollections/enum_set.rs b/src/libcollections/enum_set.rs
index 3f8c0121fafb..140c9edb5a3a 100644
--- a/src/libcollections/enum_set.rs
+++ b/src/libcollections/enum_set.rs
@@ -250,9 +250,9 @@ impl<E:CLike> Iterator for Iter<E> {
 }
 
 impl<E:CLike> FromIterator<E> for EnumSet<E> {
-    fn from_iter<I:Iterator<Item=E>>(iterator: I) -> EnumSet<E> {
+    fn from_iter<I: IntoIterator<Item=E>>(iter: I) -> EnumSet<E> {
         let mut ret = EnumSet::new();
-        ret.extend(iterator);
+        ret.extend(iter);
         ret
     }
 }
diff --git a/src/libcollections/linked_list.rs b/src/libcollections/linked_list.rs
index 0ec1371c73cb..bd8f508b70fa 100644
--- a/src/libcollections/linked_list.rs
+++ b/src/libcollections/linked_list.rs
@@ -834,9 +834,9 @@ impl<A> DoubleEndedIterator for IntoIter<A> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A> FromIterator<A> for LinkedList<A> {
-    fn from_iter<T: Iterator<Item=A>>(iterator: T) -> LinkedList<A> {
-        let mut ret = LinkedList::new();
-        ret.extend(iterator);
+    fn from_iter<T: IntoIterator<Item=A>>(iter: T) -> LinkedList<A> {
+        let mut ret = DList::new();
+        ret.extend(iter);
         ret
     }
 }
diff --git a/src/libcollections/string.rs b/src/libcollections/string.rs
index dc1158ecaf85..627c357d8b3f 100644
--- a/src/libcollections/string.rs
+++ b/src/libcollections/string.rs
@@ -709,18 +709,18 @@ impl Error for FromUtf16Error {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl FromIterator<char> for String {
-    fn from_iter<I:Iterator<Item=char>>(iterator: I) -> String {
+    fn from_iter<I: IntoIterator<Item=char>>(iter: I) -> String {
         let mut buf = String::new();
-        buf.extend(iterator);
+        buf.extend(iter);
         buf
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> FromIterator<&'a str> for String {
-    fn from_iter<I:Iterator<Item=&'a str>>(iterator: I) -> String {
+    fn from_iter<I: IntoIterator<Item=&'a str>>(iter: I) -> String {
         let mut buf = String::new();
-        buf.extend(iterator);
+        buf.extend(iter);
         buf
     }
 }
diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index e4b090e4dd7a..dd10a7582fb8 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -1407,7 +1407,8 @@ impl<T> ops::DerefMut for Vec<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> FromIterator<T> for Vec<T> {
     #[inline]
-    fn from_iter<I:Iterator<Item=T>>(mut iterator: I) -> Vec<T> {
+    fn from_iter<I: IntoIterator<Item=T>>(iterable: I) -> Vec<T> {
+        let mut iterator = iterable.into_iter();
         let (lower, _) = iterator.size_hint();
         let mut vector = Vec::with_capacity(lower);
 
@@ -1651,7 +1652,7 @@ pub type CowVec<'a, T> = Cow<'a, Vec<T>, [T]>;
 
 #[unstable(feature = "collections")]
 impl<'a, T> FromIterator<T> for CowVec<'a, T> where T: Clone {
-    fn from_iter<I: Iterator<Item=T>>(it: I) -> CowVec<'a, T> {
+    fn from_iter<I: IntoIterator<Item=T>>(it: I) -> CowVec<'a, T> {
         Cow::Owned(FromIterator::from_iter(it))
     }
 }
diff --git a/src/libcollections/vec_deque.rs b/src/libcollections/vec_deque.rs
index cc01e800f607..c281d5de0272 100644
--- a/src/libcollections/vec_deque.rs
+++ b/src/libcollections/vec_deque.rs
@@ -1701,7 +1701,8 @@ impl<A> IndexMut<usize> for VecDeque<A> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A> FromIterator<A> for VecDeque<A> {
-    fn from_iter<T: Iterator<Item=A>>(iterator: T) -> VecDeque<A> {
+    fn from_iter<T: IntoIterator<Item=A>>(iterable: T) -> VecDeque<A> {
+        let iterator = iterable.into_iter();
         let (lower, _) = iterator.size_hint();
         let mut deq = VecDeque::with_capacity(lower);
         deq.extend(iterator);
diff --git a/src/libcollections/vec_map.rs b/src/libcollections/vec_map.rs
index 7085111d6a87..4431bfddbd74 100644
--- a/src/libcollections/vec_map.rs
+++ b/src/libcollections/vec_map.rs
@@ -661,7 +661,7 @@ impl<V: fmt::Debug> fmt::Debug for VecMap<V> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<V> FromIterator<(usize, V)> for VecMap<V> {
-    fn from_iter<Iter: Iterator<Item=(usize, V)>>(iter: Iter) -> VecMap<V> {
+    fn from_iter<I: IntoIterator<Item=(usize, V)>>(iter: I) -> VecMap<V> {
         let mut map = VecMap::new();
         map.extend(iter);
         map
diff --git a/src/libcore/iter.rs b/src/libcore/iter.rs
index 2e9977cd3eb1..355bf3a28cba 100644
--- a/src/libcore/iter.rs
+++ b/src/libcore/iter.rs
@@ -113,9 +113,9 @@ impl<'a, I: Iterator + ?Sized> Iterator for &'a mut I {
 #[rustc_on_unimplemented="a collection of type `{Self}` cannot be \
                           built from an iterator over elements of type `{A}`"]
 pub trait FromIterator<A> {
-    /// Build a container with elements from an external iterator.
+    /// Build a container with elements from something iterable.
     #[stable(feature = "rust1", since = "1.0.0")]
-    fn from_iter<T: Iterator<Item=A>>(iterator: T) -> Self;
+    fn from_iter<T: IntoIterator<Item=A>>(iterator: T) -> Self;
 }
 
 /// Conversion into an `Iterator`
diff --git a/src/libcore/option.rs b/src/libcore/option.rs
index 9a89682127fb..abfef72a5dbc 100644
--- a/src/libcore/option.rs
+++ b/src/libcore/option.rs
@@ -149,7 +149,7 @@ use clone::Clone;
 use cmp::{Eq, Ord};
 use default::Default;
 use iter::{ExactSizeIterator};
-use iter::{Iterator, IteratorExt, DoubleEndedIterator, FromIterator};
+use iter::{Iterator, IteratorExt, DoubleEndedIterator, FromIterator, IntoIterator};
 use mem;
 use ops::{Deref, FnOnce};
 use result::Result::{Ok, Err};
@@ -909,7 +909,7 @@ impl<A, V: FromIterator<A>> FromIterator<Option<A>> for Option<V> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    fn from_iter<I: Iterator<Item=Option<A>>>(iter: I) -> Option<V> {
+    fn from_iter<I: IntoIterator<Item=Option<A>>>(iter: I) -> Option<V> {
         // FIXME(#11084): This could be replaced with Iterator::scan when this
         // performance bug is closed.
 
@@ -934,7 +934,7 @@ impl<A, V: FromIterator<A>> FromIterator<Option<A>> for Option<V> {
             }
         }
 
-        let mut adapter = Adapter { iter: iter, found_none: false };
+        let mut adapter = Adapter { iter: iter.into_iter(), found_none: false };
         let v: V = FromIterator::from_iter(adapter.by_ref());
 
         if adapter.found_none {
diff --git a/src/libcore/result.rs b/src/libcore/result.rs
index 1a874ee178ba..23e936a75d70 100644
--- a/src/libcore/result.rs
+++ b/src/libcore/result.rs
@@ -230,7 +230,8 @@ use self::Result::{Ok, Err};
 
 use clone::Clone;
 use fmt;
-use iter::{Iterator, IteratorExt, DoubleEndedIterator, FromIterator, ExactSizeIterator};
+use iter::{Iterator, IteratorExt, DoubleEndedIterator,
+           FromIterator, ExactSizeIterator, IntoIterator};
 use ops::{FnMut, FnOnce};
 use option::Option::{self, None, Some};
 use slice::AsSlice;
@@ -906,7 +907,7 @@ impl<A, E, V: FromIterator<A>> FromIterator<Result<A, E>> for Result<V, E> {
     /// assert!(res == Ok(vec!(2, 3)));
     /// ```
     #[inline]
-    fn from_iter<I: Iterator<Item=Result<A, E>>>(iter: I) -> Result<V, E> {
+    fn from_iter<I: IntoIterator<Item=Result<A, E>>>(iter: I) -> Result<V, E> {
         // FIXME(#11084): This could be replaced with Iterator::scan when this
         // performance bug is closed.
 
@@ -931,7 +932,7 @@ impl<A, E, V: FromIterator<A>> FromIterator<Result<A, E>> for Result<V, E> {
             }
         }
 
-        let mut adapter = Adapter { iter: iter, err: None };
+        let mut adapter = Adapter { iter: iter.into_iter(), err: None };
         let v: V = FromIterator::from_iter(adapter.by_ref());
 
         match adapter.err {
diff --git a/src/librustc/middle/check_match.rs b/src/librustc/middle/check_match.rs
index 03456f852902..3b29c43ce8ce 100644
--- a/src/librustc/middle/check_match.rs
+++ b/src/librustc/middle/check_match.rs
@@ -25,7 +25,7 @@ use middle::ty::*;
 use middle::ty;
 use std::cmp::Ordering;
 use std::fmt;
-use std::iter::{range_inclusive, AdditiveIterator, FromIterator, repeat};
+use std::iter::{range_inclusive, AdditiveIterator, FromIterator, IntoIterator, repeat};
 use std::num::Float;
 use std::slice;
 use syntax::ast::{self, DUMMY_NODE_ID, NodeId, Pat};
@@ -94,8 +94,8 @@ impl<'a> fmt::Debug for Matrix<'a> {
 }
 
 impl<'a> FromIterator<Vec<&'a Pat>> for Matrix<'a> {
-    fn from_iter<T: Iterator<Item=Vec<&'a Pat>>>(iterator: T) -> Matrix<'a> {
-        Matrix(iterator.collect())
+    fn from_iter<T: IntoIterator<Item=Vec<&'a Pat>>>(iter: T) -> Matrix<'a> {
+        Matrix(iter.into_iter().collect())
     }
 }
 
diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index 61b531054a07..0ce5b164ca13 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -1555,7 +1555,8 @@ impl<K, V, S, H> FromIterator<(K, V)> for HashMap<K, V, S>
           S: HashState<Hasher=H> + Default,
           H: hash::Hasher<Output=u64>
 {
-    fn from_iter<T: Iterator<Item=(K, V)>>(iter: T) -> HashMap<K, V, S> {
+    fn from_iter<T: IntoIterator<Item=(K, V)>>(iterable: T) -> HashMap<K, V, S> {
+        let iter = iterable.into_iter();
         let lower = iter.size_hint().0;
         let mut map = HashMap::with_capacity_and_hash_state(lower,
                                                             Default::default());
diff --git a/src/libstd/collections/hash/set.rs b/src/libstd/collections/hash/set.rs
index f5e57b78d2a6..593248fd5c60 100644
--- a/src/libstd/collections/hash/set.rs
+++ b/src/libstd/collections/hash/set.rs
@@ -622,7 +622,8 @@ impl<T, S, H> FromIterator<T> for HashSet<T, S>
           S: HashState<Hasher=H> + Default,
           H: hash::Hasher<Output=u64>
 {
-    fn from_iter<I: Iterator<Item=T>>(iter: I) -> HashSet<T, S> {
+    fn from_iter<I: IntoIterator<Item=T>>(iterable: I) -> HashSet<T, S> {
+        let iter = iterable.into_iter();
         let lower = iter.size_hint().0;
         let mut set = HashSet::with_capacity_and_hash_state(lower, Default::default());
         set.extend(iter);
diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index f25cc83b93e1..2ad07462f20f 100755
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -953,7 +953,7 @@ impl PathBuf {
 }
 
 impl<'a, P: ?Sized + 'a> iter::FromIterator<&'a P> for PathBuf where P: AsPath {
-    fn from_iter<I: Iterator<Item = &'a P>>(iter: I) -> PathBuf {
+    fn from_iter<I: IntoIterator<Item = &'a P>>(iter: I) -> PathBuf {
         let mut buf = PathBuf::new("");
         buf.extend(iter);
         buf
diff --git a/src/libstd/sys/common/wtf8.rs b/src/libstd/sys/common/wtf8.rs
index e7cb67c6287e..da5ab8e434a7 100644
--- a/src/libstd/sys/common/wtf8.rs
+++ b/src/libstd/sys/common/wtf8.rs
@@ -356,9 +356,9 @@ impl Wtf8Buf {
 /// This replaces surrogate code point pairs with supplementary code points,
 /// like concatenating ill-formed UTF-16 strings effectively would.
 impl FromIterator<CodePoint> for Wtf8Buf {
-    fn from_iter<T: Iterator<Item=CodePoint>>(iterator: T) -> Wtf8Buf {
+    fn from_iter<T: IntoIterator<Item=CodePoint>>(iter: T) -> Wtf8Buf {
         let mut string = Wtf8Buf::new();
-        string.extend(iterator);
+        string.extend(iter);
         string
     }
 }
diff --git a/src/libsyntax/owned_slice.rs b/src/libsyntax/owned_slice.rs
index 0f9a56baa170..f5201d4a8bc6 100644
--- a/src/libsyntax/owned_slice.rs
+++ b/src/libsyntax/owned_slice.rs
@@ -10,7 +10,7 @@
 
 use std::default::Default;
 use std::fmt;
-use std::iter::FromIterator;
+use std::iter::{IntoIterator, FromIterator};
 use std::ops::Deref;
 use std::vec;
 use serialize::{Encodable, Decodable, Encoder, Decoder};
@@ -77,8 +77,8 @@ impl<T: Clone> Clone for OwnedSlice<T> {
 }
 
 impl<T> FromIterator<T> for OwnedSlice<T> {
-    fn from_iter<I: Iterator<Item=T>>(iter: I) -> OwnedSlice<T> {
-        OwnedSlice::from_vec(iter.collect())
+    fn from_iter<I: IntoIterator<Item=T>>(iter: I) -> OwnedSlice<T> {
+        OwnedSlice::from_vec(iter.into_iter().collect())
     }
 }
 
diff --git a/src/libsyntax/util/small_vector.rs b/src/libsyntax/util/small_vector.rs
index 6a1fb4008ade..0a39d3809045 100644
--- a/src/libsyntax/util/small_vector.rs
+++ b/src/libsyntax/util/small_vector.rs
@@ -30,7 +30,7 @@ enum SmallVectorRepr<T> {
 }
 
 impl<T> FromIterator<T> for SmallVector<T> {
-    fn from_iter<I: Iterator<Item=T>>(iter: I) -> SmallVector<T> {
+    fn from_iter<I: IntoIterator<Item=T>>(iter: I) -> SmallVector<T> {
         let mut v = SmallVector::zero();
         v.extend(iter);
         v