diff --git a/src/libcore/cleanup.rs b/src/libcore/cleanup.rs
index 11a4cad5d1bbb72559b7ef20bfa8c2db0c1bcb8e..567d6da23a68ccdfcc0bdbc21651f71c4560595e 100644
--- a/src/libcore/cleanup.rs
+++ b/src/libcore/cleanup.rs
@@ -111,45 +111,102 @@ struct Task {
  * This runs at task death to free all boxes.
  */
 
+struct AnnihilateStats {
+    n_total_boxes: uint,
+    n_unique_boxes: uint,
+    n_bytes_freed: uint
+}
+
+unsafe fn each_live_alloc(f: fn(box: *mut BoxRepr, uniq: bool) -> bool) {
+    use managed;
+
+    let task: *Task = transmute(rustrt::rust_get_task());
+    let box = (*task).boxed_region.live_allocs;
+    let mut box: *mut BoxRepr = transmute(copy box);
+    while box != mut_null() {
+        let next = transmute(copy (*box).header.next);
+        let uniq =
+            (*box).header.ref_count == managed::raw::RC_MANAGED_UNIQUE;
+
+        if ! f(box, uniq) {
+            break
+        }
+
+        box = next
+    }
+}
+
+#[cfg(unix)]
+fn debug_mem() -> bool {
+    use os;
+    use libc;
+    do os::as_c_charp("RUST_DEBUG_MEM") |p| {
+        unsafe { libc::getenv(p) != null() }
+    }
+}
+
+#[cfg(windows)]
+fn debug_mem() -> bool {
+    false
+}
+
 /// Destroys all managed memory (i.e. @ boxes) held by the current task.
 #[cfg(notest)]
 #[lang="annihilate"]
 pub unsafe fn annihilate() {
     use rt::rt_free;
     use io::WriterUtil;
+    use io;
+    use libc;
+    use sys;
+    use managed;
 
-    let task: *Task = transmute(rustrt::rust_get_task());
+    let mut stats = AnnihilateStats {
+        n_total_boxes: 0,
+        n_unique_boxes: 0,
+        n_bytes_freed: 0
+    };
 
     // Pass 1: Make all boxes immortal.
-    let box = (*task).boxed_region.live_allocs;
-    let mut box: *mut BoxRepr = transmute(copy box);
-    while box != mut_null() {
-        debug!("making box immortal: %x", box as uint);
-        (*box).header.ref_count = 0x77777777;
-        box = transmute(copy (*box).header.next);
+    for each_live_alloc |box, uniq| {
+        stats.n_total_boxes += 1;
+        if uniq {
+            stats.n_unique_boxes += 1;
+        } else {
+            (*box).header.ref_count = managed::raw::RC_IMMORTAL;
+        }
     }
 
     // Pass 2: Drop all boxes.
-    let box = (*task).boxed_region.live_allocs;
-    let mut box: *mut BoxRepr = transmute(copy box);
-    while box != mut_null() {
-        debug!("calling drop glue for box: %x", box as uint);
-        let tydesc: *TypeDesc = transmute(copy (*box).header.type_desc);
-        let drop_glue: DropGlue = transmute(((*tydesc).drop_glue, 0));
-        drop_glue(to_unsafe_ptr(&tydesc), transmute(&(*box).data));
-
-        box = transmute(copy (*box).header.next);
+    for each_live_alloc |box, uniq| {
+        if !uniq {
+            let tydesc: *TypeDesc = transmute(copy (*box).header.type_desc);
+            let drop_glue: DropGlue = transmute(((*tydesc).drop_glue, 0));
+            drop_glue(to_unsafe_ptr(&tydesc), transmute(&(*box).data));
+        }
     }
 
     // Pass 3: Free all boxes.
-    loop {
-        let box = (*task).boxed_region.live_allocs;
-        if box == null() { break; }
-        let mut box: *mut BoxRepr = transmute(copy box);
-        assert (*box).header.prev == null();
-
-        debug!("freeing box: %x", box as uint);
-        rt_free(transmute(box));
+    for each_live_alloc |box, uniq| {
+        if !uniq {
+            stats.n_bytes_freed +=
+                (*((*box).header.type_desc)).size
+                + sys::size_of::<BoxRepr>();
+            rt_free(transmute(box));
+        }
+    }
+
+    if debug_mem() {
+        // We do logging here w/o allocation.
+        let dbg = libc::STDERR_FILENO as io::fd_t;
+        dbg.write_str("annihilator stats:");
+        dbg.write_str("\n  total_boxes: ");
+        dbg.write_uint(stats.n_total_boxes);
+        dbg.write_str("\n  unique_boxes: ");
+        dbg.write_uint(stats.n_unique_boxes);
+        dbg.write_str("\n  bytes_freed: ");
+        dbg.write_uint(stats.n_bytes_freed);
+        dbg.write_str("\n");
     }
 }
 
diff --git a/src/libcore/managed.rs b/src/libcore/managed.rs
index 0f13a8485afdb4814a2b52234b2f03895cabd264..bed50cfbc256e04c42860fbee233ac609ae02fb1 100644
--- a/src/libcore/managed.rs
+++ b/src/libcore/managed.rs
@@ -16,7 +16,13 @@
 use prelude::*;
 use ptr;
 
+
 pub mod raw {
+
+    pub const RC_EXCHANGE_UNIQUE : uint = (-1) as uint;
+    pub const RC_MANAGED_UNIQUE : uint = (-2) as uint;
+    pub const RC_IMMORTAL : uint = 0x77777777;
+
     use intrinsic::TyDesc;
 
     pub struct BoxHeaderRepr {
diff --git a/src/libcore/vec.rs b/src/libcore/vec.rs
index 97162568d57a6b49877661dc52d7518b4d8118f1..31c837e7e8a3a9e93857a41d1c9a802f623a0384 100644
--- a/src/libcore/vec.rs
+++ b/src/libcore/vec.rs
@@ -1,4 +1,4 @@
-// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -31,9 +31,14 @@
 
 #[abi = "cdecl"]
 pub extern mod rustrt {
+    // These names are terrible. reserve_shared applies
+    // to ~[] and reserve_shared_actual applies to @[].
     unsafe fn vec_reserve_shared(++t: *sys::TypeDesc,
                                  ++v: **raw::VecRepr,
                                  ++n: libc::size_t);
+    unsafe fn vec_reserve_shared_actual(++t: *sys::TypeDesc,
+                                        ++v: **raw::VecRepr,
+                                        ++n: libc::size_t);
 }
 
 /// Returns true if a vector contains no elements
@@ -59,11 +64,17 @@ unsafe fn vec_reserve_shared(++t: *sys::TypeDesc,
  */
 pub fn reserve<T>(v: &mut ~[T], n: uint) {
     // Only make the (slow) call into the runtime if we have to
+    use managed;
     if capacity(v) < n {
         unsafe {
             let ptr: **raw::VecRepr = cast::transmute(v);
-            rustrt::vec_reserve_shared(sys::get_type_desc::<T>(),
-                                       ptr, n as size_t);
+            let td = sys::get_type_desc::<T>();
+            if ((**ptr).box_header.ref_count ==
+                managed::raw::RC_MANAGED_UNIQUE) {
+                rustrt::vec_reserve_shared_actual(td, ptr, n as size_t);
+            } else {
+                rustrt::vec_reserve_shared(td, ptr, n as size_t);
+            }
         }
     }
 }
diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
index cadbe1208ad2b37320a0a057874c2cab07ea1c91..9e3be94294acab2d50e924c1c07fd0c02dc7f509 100644
--- a/src/librustc/middle/trans/base.rs
+++ b/src/librustc/middle/trans/base.rs
@@ -286,7 +286,7 @@ pub fn malloc_raw_dyn(bcx: block,
     let ccx = bcx.ccx();
 
     let (mk_fn, langcall) = match heap {
-        heap_shared => {
+        heap_managed | heap_managed_unique => {
             (ty::mk_imm_box, bcx.tcx().lang_items.malloc_fn())
         }
         heap_exchange => {
@@ -310,7 +310,9 @@ pub fn malloc_raw_dyn(bcx: block,
         langcall,
         ~[tydesc, size],
         expr::SaveIn(rval));
-    return rslt(bcx, PointerCast(bcx, Load(bcx, rval), llty));
+    let r = rslt(bcx, PointerCast(bcx, Load(bcx, rval), llty));
+    maybe_set_managed_unique_rc(r.bcx, r.val, heap);
+    r
 }
 
 /**
@@ -364,11 +366,31 @@ pub fn malloc_general(bcx: block, t: ty::t, heap: heap)
 }
 pub fn malloc_boxed(bcx: block, t: ty::t)
     -> MallocResult {
-    malloc_general(bcx, t, heap_shared)
+    malloc_general(bcx, t, heap_managed)
 }
+
+pub fn heap_for_unique(bcx: block, t: ty::t) -> heap {
+    if ty::type_contents(bcx.tcx(), t).contains_managed() {
+        heap_managed_unique
+    } else {
+        heap_exchange
+    }
+}
+
+pub fn maybe_set_managed_unique_rc(bcx: block, bx: ValueRef, heap: heap) {
+    if heap == heap_managed_unique {
+        // In cases where we are looking at a unique-typed allocation in the
+        // managed heap (thus have refcount 1 from the managed allocator),
+        // such as a ~(@foo) or such. These need to have their refcount forced
+        // to -2 so the annihilator ignores them.
+        let rc = GEPi(bcx, bx, [0u, abi::box_field_refcnt]);
+        Store(bcx, C_int(bcx.ccx(), -2), rc);
+    }
+}
+
 pub fn malloc_unique(bcx: block, t: ty::t)
     -> MallocResult {
-    malloc_general(bcx, t, heap_exchange)
+    malloc_general(bcx, t, heap_for_unique(bcx, t))
 }
 
 // Type descriptor and type glue stuff
diff --git a/src/librustc/middle/trans/closure.rs b/src/librustc/middle/trans/closure.rs
index 94051f1ce13d604fe642ce972fca14a186e250e1..dc68eff9c7f64e29c9132b42360aaa8f27b23d62 100644
--- a/src/librustc/middle/trans/closure.rs
+++ b/src/librustc/middle/trans/closure.rs
@@ -178,10 +178,10 @@ fn nuke_ref_count(bcx: block, llbox: ValueRef) {
     // Allocate and initialize the box:
     match sigil {
         ast::ManagedSigil => {
-            malloc_raw(bcx, cdata_ty, heap_shared)
+            malloc_raw(bcx, cdata_ty, heap_managed)
         }
         ast::OwnedSigil => {
-            malloc_raw(bcx, cdata_ty, heap_exchange)
+            malloc_raw(bcx, cdata_ty, heap_for_unique(bcx, cdata_ty))
         }
         ast::BorrowedSigil => {
             let cbox_ty = tuplify_box_ty(tcx, cdata_ty);
@@ -574,7 +574,7 @@ pub fn make_opaque_cbox_free_glue(
         // Free the ty descr (if necc) and the box itself
         match sigil {
             ast::ManagedSigil => glue::trans_free(bcx, cbox),
-            ast::OwnedSigil => glue::trans_unique_free(bcx, cbox),
+            ast::OwnedSigil => glue::trans_exchange_free(bcx, cbox),
             ast::BorrowedSigil => {
                 bcx.sess().bug(~"impossible")
             }
diff --git a/src/librustc/middle/trans/common.rs b/src/librustc/middle/trans/common.rs
index 8bd85be0f70824815dd41f7c68f29d7fb3560007..b58e374320ae6369523a497aad1a5c005c8d15d8 100644
--- a/src/librustc/middle/trans/common.rs
+++ b/src/librustc/middle/trans/common.rs
@@ -332,8 +332,10 @@ pub fn warn_not_to_commit(ccx: @CrateContext, msg: ~str) {
 }
 
 // Heap selectors. Indicate which heap something should go on.
+#[deriving_eq]
 pub enum heap {
-    heap_shared,
+    heap_managed,
+    heap_managed_unique,
     heap_exchange,
 }
 
@@ -458,12 +460,12 @@ pub fn add_clean_frozen_root(bcx: block, val: ValueRef, t: ty::t) {
 }
 pub fn add_clean_free(cx: block, ptr: ValueRef, heap: heap) {
     let free_fn = match heap {
-      heap_shared => {
+      heap_managed | heap_managed_unique => {
         let f: @fn(block) -> block = |a| glue::trans_free(a, ptr);
         f
       }
       heap_exchange => {
-        let f: @fn(block) -> block = |a| glue::trans_unique_free(a, ptr);
+        let f: @fn(block) -> block = |a| glue::trans_exchange_free(a, ptr);
         f
       }
     };
diff --git a/src/librustc/middle/trans/expr.rs b/src/librustc/middle/trans/expr.rs
index ad171a44859d19b5834acabbc91a32cd24ad1c5a..83265975b50652dd2c55dd987cce1ab655034b72 100644
--- a/src/librustc/middle/trans/expr.rs
+++ b/src/librustc/middle/trans/expr.rs
@@ -414,11 +414,12 @@ fn trans_rvalue_datum_unadjusted(bcx: block, expr: @ast::expr) -> DatumBlock {
     match expr.node {
         ast::expr_vstore(contents, ast::expr_vstore_box) |
         ast::expr_vstore(contents, ast::expr_vstore_mut_box) => {
-            return tvec::trans_uniq_or_managed_vstore(bcx, heap_shared,
+            return tvec::trans_uniq_or_managed_vstore(bcx, heap_managed,
                                                       expr, contents);
         }
         ast::expr_vstore(contents, ast::expr_vstore_uniq) => {
-            return tvec::trans_uniq_or_managed_vstore(bcx, heap_exchange,
+            let heap = heap_for_unique(bcx, expr_ty(bcx, contents));
+            return tvec::trans_uniq_or_managed_vstore(bcx, heap,
                                                       expr, contents);
         }
         ast::expr_lit(lit) => {
@@ -1272,10 +1273,12 @@ fn trans_unary_datum(bcx: block,
             immediate_rvalue_bcx(bcx, llneg, un_ty)
         }
         ast::box(_) => {
-            trans_boxed_expr(bcx, un_ty, sub_expr, sub_ty, heap_shared)
+            trans_boxed_expr(bcx, un_ty, sub_expr, sub_ty,
+                             heap_managed)
         }
         ast::uniq(_) => {
-            trans_boxed_expr(bcx, un_ty, sub_expr, sub_ty, heap_exchange)
+            let heap  = heap_for_unique(bcx, un_ty);
+            trans_boxed_expr(bcx, un_ty, sub_expr, sub_ty, heap)
         }
         ast::deref => {
             bcx.sess().bug(~"deref expressions should have been \
diff --git a/src/librustc/middle/trans/glue.rs b/src/librustc/middle/trans/glue.rs
index bbe80431c07fb715832ac7db86d12af462ef86fa..cd3a14b69e71d72a70725459519b9558192f1520 100644
--- a/src/librustc/middle/trans/glue.rs
+++ b/src/librustc/middle/trans/glue.rs
@@ -37,8 +37,8 @@ pub fn trans_free(cx: block, v: ValueRef) -> block {
         expr::Ignore)
 }
 
-pub fn trans_unique_free(cx: block, v: ValueRef) -> block {
-    let _icx = cx.insn_ctxt("trans_unique_free");
+pub fn trans_exchange_free(cx: block, v: ValueRef) -> block {
+    let _icx = cx.insn_ctxt("trans_exchange_free");
     callee::trans_rtcall_or_lang_call(
         cx,
         cx.tcx().lang_items.exchange_free_fn(),
diff --git a/src/librustc/middle/trans/meth.rs b/src/librustc/middle/trans/meth.rs
index ac050a74df442af248e7472b3d1e5114b8a8181c..02ea29f915d69e7c8331657f93c20ceaa7cdba54 100644
--- a/src/librustc/middle/trans/meth.rs
+++ b/src/librustc/middle/trans/meth.rs
@@ -878,7 +878,7 @@ pub fn trans_trait_cast(bcx: block,
                 let MallocResult {bcx: new_bcx, box: llbox, body: body} =
                     malloc_boxed(bcx, v_ty);
                 bcx = new_bcx;
-                add_clean_free(bcx, llbox, heap_shared);
+                add_clean_free(bcx, llbox, heap_managed);
                 bcx = expr::trans_into(bcx, val, SaveIn(body));
                 revoke_clean(bcx, llbox);
 
diff --git a/src/librustc/middle/trans/tvec.rs b/src/librustc/middle/trans/tvec.rs
index caf70f7b239d06d4d4bac2b8276ad002edaf2e88..345a20aa5fc69ea01b50cdff3d3a865319fd3652 100644
--- a/src/librustc/middle/trans/tvec.rs
+++ b/src/librustc/middle/trans/tvec.rs
@@ -85,11 +85,13 @@ pub fn alloc_raw(bcx: block, unit_ty: ty::t,
         base::malloc_general_dyn(bcx, vecbodyty, heap, vecsize);
     Store(bcx, fill, GEPi(bcx, body, [0u, abi::vec_elt_fill]));
     Store(bcx, alloc, GEPi(bcx, body, [0u, abi::vec_elt_alloc]));
+    base::maybe_set_managed_unique_rc(bcx, bx, heap);
     return rslt(bcx, bx);
 }
+
 pub fn alloc_uniq_raw(bcx: block, unit_ty: ty::t,
                       fill: ValueRef, alloc: ValueRef) -> Result {
-    alloc_raw(bcx, unit_ty, fill, alloc, heap_exchange)
+    alloc_raw(bcx, unit_ty, fill, alloc, heap_for_unique(bcx, unit_ty))
 }
 
 pub fn alloc_vec(bcx: block,
@@ -317,13 +319,14 @@ pub fn trans_uniq_or_managed_vstore(bcx: block,
                 _ => {}
             }
         }
-        heap_shared => {}
+        heap_managed | heap_managed_unique => {}
     }
 
     let vt = vec_types_from_expr(bcx, vstore_expr);
     let count = elements_required(bcx, content_expr);
 
     let Result {bcx, val} = alloc_vec(bcx, vt.unit_ty, count, heap);
+
     add_clean_free(bcx, val, heap);
     let dataptr = get_dataptr(bcx, get_bodyptr(bcx, val));
 
diff --git a/src/librustc/middle/trans/uniq.rs b/src/librustc/middle/trans/uniq.rs
index e2b1a1485eed711f716b5ed7236ef53eec1844d2..aa02cc4bf5d53ec9996ba8cddb73620cf9988c8b 100644
--- a/src/librustc/middle/trans/uniq.rs
+++ b/src/librustc/middle/trans/uniq.rs
@@ -30,7 +30,11 @@ pub fn make_free_glue(bcx: block, vptrptr: ValueRef, box_ty: ty::t)
         let body_datum = box_datum.box_body(bcx);
         let bcx = glue::drop_ty(bcx, body_datum.to_ref_llval(bcx),
                                 body_datum.ty);
-        glue::trans_unique_free(bcx, box_datum.val)
+        if ty::type_contents(bcx.tcx(), box_ty).contains_managed() {
+            glue::trans_free(bcx, box_datum.val)
+        } else {
+            glue::trans_exchange_free(bcx, box_datum.val)
+        }
     }
 }
 
diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs
index 79061dbb66c7d0af91387856dc5d0a16ecd4e51a..fdcbf2d995714ff6a104c16868e93479444c9357 100644
--- a/src/librustc/middle/ty.rs
+++ b/src/librustc/middle/ty.rs
@@ -1571,10 +1571,11 @@ pub fn get_element_type(ty: t, i: uint) -> t {
 
 pub pure fn type_is_unique(ty: t) -> bool {
     match get(ty).sty {
-      ty_uniq(_) => return true,
-      ty_evec(_, vstore_uniq) => true,
-      ty_estr(vstore_uniq) => true,
-      _ => return false
+        ty_uniq(_) |
+        ty_evec(_, vstore_uniq) |
+        ty_estr(vstore_uniq) |
+        ty_opaque_closure_ptr(ast::OwnedSigil) => true,
+        _ => return false
     }
 }
 
@@ -1799,6 +1800,10 @@ fn is_owned(&self, cx: ctxt) -> bool {
         TC_MANAGED + TC_BORROWED_POINTER
     }
 
+    fn contains_managed(&self) -> bool {
+        self.intersects(TC_MANAGED)
+    }
+
     fn is_const(&self, cx: ctxt) -> bool {
         !self.intersects(TypeContents::nonconst(cx))
     }
@@ -2083,11 +2088,19 @@ fn tc_ty(cx: ctxt,
                 TC_ALL
             }
 
-            ty_trait(_, _, vstore_fixed(_)) |
-            ty_type |
-            ty_opaque_closure_ptr(_) |
-            ty_opaque_box |
-            ty_unboxed_vec(_) |
+            ty_opaque_box => TC_MANAGED,
+            ty_unboxed_vec(mt) => tc_mt(cx, mt, cache),
+            ty_opaque_closure_ptr(sigil) => {
+                match sigil {
+                    ast::BorrowedSigil => TC_BORROWED_POINTER,
+                    ast::ManagedSigil => TC_MANAGED,
+                    ast::OwnedSigil => TC_OWNED_CLOSURE
+                }
+            }
+
+            ty_type => TC_NONE,
+            ty_trait(_, _, vstore_fixed(_)) => TC_NONE,
+
             ty_err => {
                 cx.sess.bug(~"Asked to compute contents of fictitious type");
             }
@@ -2229,8 +2242,11 @@ fn type_size(cx: ctxt, ty: t) -> uint {
           ty_infer(_) => {
             cx.sess.bug(~"Asked to compute kind of a type variable");
           }
-          ty_type | ty_opaque_closure_ptr(_)
-          | ty_opaque_box | ty_unboxed_vec(_) | ty_err => {
+          ty_type => 1,
+          ty_opaque_closure_ptr(_) => 1,
+          ty_opaque_box => 1,
+          ty_unboxed_vec(_) => 10,
+          ty_err => {
             cx.sess.bug(~"Asked to compute kind of fictitious type");
           }
         }
diff --git a/src/rt/boxed_region.cpp b/src/rt/boxed_region.cpp
index c9734f460c5e3ddfbd18734efa3211afcb696b08..d159df03dc3c0c3fc2ccd97c0d20adfcca6bc80b 100644
--- a/src/rt/boxed_region.cpp
+++ b/src/rt/boxed_region.cpp
@@ -38,7 +38,10 @@ rust_opaque_box *boxed_region::malloc(type_desc *td, size_t body_size) {
 
 rust_opaque_box *boxed_region::realloc(rust_opaque_box *box,
                                        size_t new_size) {
-    assert(box->ref_count == 1);
+
+    // We also get called on the unique-vec-in-managed-heap path.
+    assert(box->ref_count == 1 ||
+           box->ref_count == (size_t)(-2));
 
     size_t total_size = new_size + sizeof(rust_opaque_box);
     rust_opaque_box *new_box =
@@ -47,7 +50,6 @@ rust_opaque_box *boxed_region::realloc(rust_opaque_box *box,
     if (new_box->next) new_box->next->prev = new_box;
     if (live_allocs == box) live_allocs = new_box;
 
-
     LOG(rust_get_current_task(), box,
         "@realloc()=%p with orig=%p, size %lu==%lu+%lu",
         new_box, box, total_size, sizeof(rust_opaque_box), new_size);