diff --git a/.gitignore b/.gitignore
index f7f1d31ef48..cc4f185bafd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -74,6 +74,7 @@ src/.DS_Store
 /doc/html
 /doc/latex
 /doc/std
+/doc/arena
 /doc/extra
 /doc/flate
 /doc/green
diff --git a/doc/index.md b/doc/index.md
index 16c6db3859c..bfd81a1d85f 100644
--- a/doc/index.md
+++ b/doc/index.md
@@ -37,6 +37,7 @@ li {list-style-type: none; }
 * [The Rust parser, `libsyntax`](syntax/index.html)
 * [The Rust compiler, `librustc`](rustc/index.html)
 
+* [The `arena` allocation library](arena/index.html)
 * [The `flate` compression library](flate/index.html)
 
 # Tooling
diff --git a/mk/crates.mk b/mk/crates.mk
index dc374549dad..c865a37b8ec 100644
--- a/mk/crates.mk
+++ b/mk/crates.mk
@@ -49,7 +49,7 @@
 # automatically generated for all stage/host/target combinations.
 ################################################################################
 
-TARGET_CRATES := std extra green rustuv native flate
+TARGET_CRATES := std extra green rustuv native flate arena
 HOST_CRATES := syntax rustc rustdoc rustpkg
 CRATES := $(TARGET_CRATES) $(HOST_CRATES)
 TOOLS := compiletest rustpkg rustdoc rustc
@@ -60,10 +60,11 @@ DEPS_green := std
 DEPS_rustuv := std native:uv native:uv_support
 DEPS_native := std
 DEPS_syntax := std extra
-DEPS_rustc := syntax native:rustllvm flate
+DEPS_rustc := syntax native:rustllvm flate arena
 DEPS_rustdoc := rustc native:sundown
 DEPS_rustpkg := rustc
 DEPS_flate := std native:miniz
+DEPS_arena := std extra
 
 TOOL_DEPS_compiletest := extra green rustuv
 TOOL_DEPS_rustpkg := rustpkg green rustuv
diff --git a/src/libextra/arena.rs b/src/libarena/lib.rs
similarity index 98%
rename from src/libextra/arena.rs
rename to src/libarena/lib.rs
index 87f6e27b632..27dad55c429 100644
--- a/src/libextra/arena.rs
+++ b/src/libarena/lib.rs
@@ -15,10 +15,17 @@
 //! of individual objects while the arena itself is still alive. The benefit
 //! of an arena is very fast allocation; just a pointer bump.
 
+#[crate_id = "arena#0.10-pre"];
+#[crate_type = "rlib"];
+#[crate_type = "dylib"];
+#[license = "MIT/ASL2"];
 #[allow(missing_doc)];
+#[feature(managed_boxes)];
 
-use list::{List, Cons, Nil};
-use list;
+extern mod extra;
+
+use extra::list::{List, Cons, Nil};
+use extra::list;
 
 use std::at_vec;
 use std::cast::{transmute, transmute_mut, transmute_mut_region};
@@ -493,7 +500,7 @@ impl<T> Drop for TypedArena<T> {
 #[cfg(test)]
 mod test {
     use super::{Arena, TypedArena};
-    use test::BenchHarness;
+    use extra::test::BenchHarness;
 
     struct Point {
         x: int,
diff --git a/src/libextra/lib.rs b/src/libextra/lib.rs
index 5a4fedd2b2a..6e3f5fd4b95 100644
--- a/src/libextra/lib.rs
+++ b/src/libextra/lib.rs
@@ -70,7 +70,6 @@ pub mod tempfile;
 pub mod glob;
 pub mod term;
 pub mod time;
-pub mod arena;
 pub mod base64;
 pub mod workcache;
 pub mod enum_set;
diff --git a/src/librustc/lib.rs b/src/librustc/lib.rs
index 9056d6e5d4f..c840faecb55 100644
--- a/src/librustc/lib.rs
+++ b/src/librustc/lib.rs
@@ -31,6 +31,7 @@ This API is completely unstable and subject to change.
 
 extern mod extra;
 extern mod flate;
+extern mod arena;
 extern mod syntax;
 
 use back::link;
diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
index 87667d3ff48..44349cc892b 100644
--- a/src/librustc/middle/trans/base.rs
+++ b/src/librustc/middle/trans/base.rs
@@ -68,7 +68,7 @@ use util::common::indenter;
 use util::ppaux::{Repr, ty_to_str};
 use util::sha2::Sha256;
 
-use extra::arena::TypedArena;
+use arena::TypedArena;
 use extra::time;
 use std::c_str::ToCStr;
 use std::cell::{Cell, RefCell};
diff --git a/src/librustc/middle/trans/common.rs b/src/librustc/middle/trans/common.rs
index 38badc20c19..18a6727dee0 100644
--- a/src/librustc/middle/trans/common.rs
+++ b/src/librustc/middle/trans/common.rs
@@ -31,7 +31,7 @@ use middle::typeck;
 use util::ppaux::Repr;
 
 
-use extra::arena::TypedArena;
+use arena::TypedArena;
 use std::c_str::ToCStr;
 use std::cast::transmute;
 use std::cast;
diff --git a/src/librustc/middle/typeck/variance.rs b/src/librustc/middle/typeck/variance.rs
index c2608967313..dc57ad747eb 100644
--- a/src/librustc/middle/typeck/variance.rs
+++ b/src/librustc/middle/typeck/variance.rs
@@ -193,8 +193,8 @@ represents the "variance transform" as defined in the paper:
 */
 
 use std::hashmap::HashMap;
-use extra::arena;
-use extra::arena::Arena;
+use arena;
+use arena::Arena;
 use middle::ty;
 use std::vec;
 use syntax::ast;
diff --git a/src/test/bench/shootout-binarytrees.rs b/src/test/bench/shootout-binarytrees.rs
index 7abbbdd278c..5b0a90f280d 100644
--- a/src/test/bench/shootout-binarytrees.rs
+++ b/src/test/bench/shootout-binarytrees.rs
@@ -9,10 +9,11 @@
 // except according to those terms.
 
 extern mod extra;
+extern mod arena;
 
 use std::iter::range_step;
 use extra::future::Future;
-use extra::arena::TypedArena;
+use arena::TypedArena;
 
 enum Tree<'a> {
     Nil,
diff --git a/src/test/run-pass/placement-new-arena.rs b/src/test/run-pass/placement-new-arena.rs
index 238ea7485c9..3e26dc69a84 100644
--- a/src/test/run-pass/placement-new-arena.rs
+++ b/src/test/run-pass/placement-new-arena.rs
@@ -10,8 +10,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-extern mod extra;
-use extra::arena::Arena;
+extern mod arena;
+use arena::Arena;
 
 pub fn main() {
     let mut arena = Arena::new();
diff --git a/src/test/run-pass/regions-mock-tcx.rs b/src/test/run-pass/regions-mock-tcx.rs
index 71b9e3ee7ba..3b5893358bf 100644
--- a/src/test/run-pass/regions-mock-tcx.rs
+++ b/src/test/run-pass/regions-mock-tcx.rs
@@ -16,10 +16,9 @@
 // - Multiple lifetime parameters
 // - Arenas
 
-extern mod extra;
+extern mod arena;
 
-use extra::arena;
-use extra::arena::Arena;
+use arena::Arena;
 use std::hashmap::HashMap;
 use std::cast;
 use std::libc;