diff --git a/src/librustc_trans/trans/attributes.rs b/src/librustc_trans/trans/attributes.rs
index 4bb2b13998f7..6c99632341fb 100644
--- a/src/librustc_trans/trans/attributes.rs
+++ b/src/librustc_trans/trans/attributes.rs
@@ -13,13 +13,11 @@ use libc::{c_uint, c_ulonglong};
 use llvm::{self, ValueRef, AttrHelper};
 use middle::ty;
 use middle::infer;
-use middle::traits::ProjectionMode;
 use session::config::NoDebugInfo;
 pub use syntax::attr::InlineAttr;
 use syntax::ast;
 use rustc_front::hir;
 use trans::abi::Abi;
-use trans::base;
 use trans::common;
 use trans::context::CrateContext;
 use trans::machine;
@@ -130,21 +128,12 @@ pub fn from_fn_type<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, fn_type: ty::Ty<'tcx
                               -> llvm::AttrBuilder {
     use middle::ty::{BrAnon, ReLateBound};
 
-    let function_type;
-    let (fn_sig, abi, env_ty) = match fn_type.sty {
-        ty::TyFnDef(_, _, ref f) | ty::TyFnPtr(ref f) => (&f.sig, f.abi, None),
-        ty::TyClosure(closure_did, ref substs) => {
-            let infcx = infer::normalizing_infer_ctxt(ccx.tcx(),
-                                                      &ccx.tcx().tables,
-                                                      ProjectionMode::Any);
-            function_type = infcx.closure_type(closure_did, substs);
-            let self_type = base::self_type_for_closure(ccx, closure_did, fn_type);
-            (&function_type.sig, Abi::RustCall, Some(self_type))
-        }
-        _ => ccx.sess().bug("expected closure or function.")
+    let f = match fn_type.sty {
+        ty::TyFnDef(_, _, f) | ty::TyFnPtr(f) => f,
+        _ => unreachable!("expected fn type, found {:?}", fn_type)
     };
 
-    let fn_sig = ccx.tcx().erase_late_bound_regions(fn_sig);
+    let fn_sig = ccx.tcx().erase_late_bound_regions(&f.sig);
     let fn_sig = infer::normalize_associated_type(ccx.tcx(), &fn_sig);
 
     let mut attrs = llvm::AttrBuilder::new();
@@ -153,30 +142,17 @@ pub fn from_fn_type<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, fn_type: ty::Ty<'tcx
     // These have an odd calling convention, so we need to manually
     // unpack the input ty's
     let input_tys = match fn_type.sty {
-        ty::TyClosure(..) => {
-            assert!(abi == Abi::RustCall);
-
-            match fn_sig.inputs[0].sty {
-                ty::TyTuple(ref inputs) => {
-                    let mut full_inputs = vec![env_ty.expect("Missing closure environment")];
-                    full_inputs.extend_from_slice(inputs);
-                    full_inputs
-                }
-                _ => ccx.sess().bug("expected tuple'd inputs")
-            }
-        },
-        ty::TyFnDef(..) | ty::TyFnPtr(_) if abi == Abi::RustCall => {
-            let mut inputs = vec![fn_sig.inputs[0]];
+        ty::TyFnDef(..) | ty::TyFnPtr(_) if f.abi == Abi::RustCall => {
+            let first = Some(fn_sig.inputs[0]).into_iter();
 
             match fn_sig.inputs[1].sty {
                 ty::TyTuple(ref t_in) => {
-                    inputs.extend_from_slice(&t_in[..]);
-                    inputs
+                    first.chain(t_in.iter().cloned())
                 }
                 _ => ccx.sess().bug("expected tuple'd inputs")
             }
         }
-        _ => fn_sig.inputs.clone()
+        _ => None.into_iter().chain(fn_sig.inputs.iter().cloned())
     };
 
     // Index 0 is the return value of the llvm func, so we start at 1
@@ -228,7 +204,7 @@ pub fn from_fn_type<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, fn_type: ty::Ty<'tcx
         }
     }
 
-    for &t in input_tys.iter() {
+    for t in input_tys {
         match t.sty {
             _ if type_of::arg_is_indirect(ccx, t) => {
                 let llarg_sz = machine::llsize_of_real(ccx, type_of::type_of(ccx, t));
diff --git a/src/librustc_trans/trans/base.rs b/src/librustc_trans/trans/base.rs
index 69b296edd306..905ccda198c5 100644
--- a/src/librustc_trans/trans/base.rs
+++ b/src/librustc_trans/trans/base.rs
@@ -192,22 +192,6 @@ impl<'a, 'tcx> Drop for StatRecorder<'a, 'tcx> {
     }
 }
 
-pub fn self_type_for_closure<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
-                                       closure_id: DefId,
-                                       fn_ty: Ty<'tcx>)
-                                       -> Ty<'tcx> {
-    let closure_kind = ccx.tcx().closure_kind(closure_id);
-    match closure_kind {
-        ty::ClosureKind::Fn => {
-            ccx.tcx().mk_imm_ref(ccx.tcx().mk_region(ty::ReStatic), fn_ty)
-        }
-        ty::ClosureKind::FnMut => {
-            ccx.tcx().mk_mut_ref(ccx.tcx().mk_region(ty::ReStatic), fn_ty)
-        }
-        ty::ClosureKind::FnOnce => fn_ty,
-    }
-}
-
 pub fn kind_for_closure(ccx: &CrateContext, closure_id: DefId) -> ty::ClosureKind {
     *ccx.tcx().tables.borrow().closure_kinds.get(&closure_id).unwrap()
 }
diff --git a/src/librustc_trans/trans/closure.rs b/src/librustc_trans/trans/closure.rs
index d4272e791850..df8dd1a09b7a 100644
--- a/src/librustc_trans/trans/closure.rs
+++ b/src/librustc_trans/trans/closure.rs
@@ -14,7 +14,7 @@ use llvm::{ValueRef, get_params};
 use middle::def_id::DefId;
 use middle::infer;
 use middle::traits::ProjectionMode;
-use trans::abi::Abi::RustCall;
+use trans::abi::Abi;
 use trans::adt;
 use trans::attributes;
 use trans::base::*;
@@ -30,7 +30,7 @@ use trans::monomorphize::{Instance};
 use trans::type_of::*;
 use trans::value::Value;
 use trans::Disr;
-use middle::ty;
+use middle::ty::{self, Ty, TyCtxt};
 use session::config::FullDebugInfo;
 
 use syntax::ast;
@@ -49,7 +49,7 @@ fn load_closure_environment<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 
     // Special case for small by-value selfs.
     let closure_ty = node_id_type(bcx, bcx.fcx.id);
-    let self_type = self_type_for_closure(bcx.ccx(), closure_def_id, closure_ty);
+    let self_type = get_self_type(bcx.tcx(), closure_def_id, closure_ty);
     let kind = kind_for_closure(bcx.ccx(), closure_def_id);
     let llenv = if kind == ty::ClosureKind::FnOnce &&
             !arg_is_indirect(bcx.ccx(), self_type) {
@@ -131,6 +131,21 @@ impl<'a> ClosureEnv<'a> {
     }
 }
 
+pub fn get_self_type<'tcx>(tcx: &TyCtxt<'tcx>,
+                           closure_id: DefId,
+                           fn_ty: Ty<'tcx>)
+                           -> Ty<'tcx> {
+    match tcx.closure_kind(closure_id) {
+        ty::ClosureKind::Fn => {
+            tcx.mk_imm_ref(tcx.mk_region(ty::ReStatic), fn_ty)
+        }
+        ty::ClosureKind::FnMut => {
+            tcx.mk_mut_ref(tcx.mk_region(ty::ReStatic), fn_ty)
+        }
+        ty::ClosureKind::FnOnce => fn_ty,
+    }
+}
+
 /// Returns the LLVM function declaration for a closure, creating it if
 /// necessary. If the ID does not correspond to a closure ID, returns None.
 pub fn get_or_create_closure_declaration<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
@@ -139,22 +154,38 @@ pub fn get_or_create_closure_declaration<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
                                                    -> ValueRef {
     // Normalize type so differences in regions and typedefs don't cause
     // duplicate declarations
-    let substs = ccx.tcx().erase_regions(substs);
-    let mono_id = Instance {
+    let tcx = ccx.tcx();
+    let substs = tcx.erase_regions(substs);
+    let instance = Instance {
         def: closure_id,
         params: &substs.func_substs.types
     };
 
-    if let Some(&llfn) = ccx.closure_vals().borrow().get(&mono_id) {
+    if let Some(&llfn) = ccx.instances().borrow().get(&instance) {
         debug!("get_or_create_closure_declaration(): found closure {:?}: {:?}",
-               mono_id, Value(llfn));
+               instance, Value(llfn));
         return llfn;
     }
 
-    let path = ccx.tcx().def_path(closure_id);
+    let path = tcx.def_path(closure_id);
     let symbol = mangle_internal_name_by_path_and_seq(path, "closure");
 
-    let function_type = ccx.tcx().mk_closure_from_closure_substs(closure_id, Box::new(substs));
+    // Compute the rust-call form of the closure call method.
+    let infcx = infer::normalizing_infer_ctxt(tcx, &tcx.tables, ProjectionMode::Any);
+    let sig = &infcx.closure_type(closure_id, &substs).sig;
+    let sig = tcx.erase_late_bound_regions(sig);
+    let sig = infer::normalize_associated_type(tcx, &sig);
+    let closure_type = tcx.mk_closure_from_closure_substs(closure_id, Box::new(substs));
+    let function_type = tcx.mk_fn_ptr(ty::BareFnTy {
+        unsafety: hir::Unsafety::Normal,
+        abi: Abi::RustCall,
+        sig: ty::Binder(ty::FnSig {
+            inputs: Some(get_self_type(tcx, closure_id, closure_type))
+                        .into_iter().chain(sig.inputs).collect(),
+            output: sig.output,
+            variadic: false
+        })
+    });
     let llfn = declare::define_internal_fn(ccx, &symbol, function_type);
 
     // set an inline hint for all closures
@@ -162,8 +193,8 @@ pub fn get_or_create_closure_declaration<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
 
     debug!("get_or_create_declaration_if_closure(): inserting new \
             closure {:?}: {:?}",
-           mono_id, Value(llfn));
-    ccx.closure_vals().borrow_mut().insert(mono_id, llfn);
+           instance, Value(llfn));
+    ccx.instances().borrow_mut().insert(instance, llfn);
 
     llfn
 }
@@ -347,7 +378,7 @@ fn trans_fn_once_adapter_shim<'a, 'tcx>(
 
     // Make a version of the closure type with the same arguments, but
     // with argument #0 being by value.
-    assert_eq!(abi, RustCall);
+    assert_eq!(abi, Abi::RustCall);
     sig.0.inputs[0] = closure_ty;
     let llonce_fn_ty = tcx.mk_fn_ptr(ty::BareFnTy {
         unsafety: unsafety,
diff --git a/src/librustc_trans/trans/declare.rs b/src/librustc_trans/trans/declare.rs
index 848ed2c1211f..7bee48039359 100644
--- a/src/librustc_trans/trans/declare.rs
+++ b/src/librustc_trans/trans/declare.rs
@@ -22,10 +22,8 @@
 use llvm::{self, ValueRef};
 use middle::ty;
 use middle::infer;
-use middle::traits::ProjectionMode;
 use trans::abi::{Abi, FnType};
 use trans::attributes;
-use trans::base;
 use trans::context::CrateContext;
 use trans::type_::Type;
 use trans::type_of;
@@ -94,37 +92,21 @@ pub fn declare_cfn(ccx: &CrateContext, name: &str, fn_type: Type) -> ValueRef {
 /// update the declaration and return existing ValueRef instead.
 pub fn declare_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, name: &str,
                             fn_type: ty::Ty<'tcx>) -> ValueRef {
-    debug!("declare_rust_fn(name={:?}, fn_type={:?})", name,
-           fn_type);
+    debug!("declare_rust_fn(name={:?}, fn_type={:?})", name, fn_type);
 
-    let function_type; // placeholder so that the memory ownership works out ok
-    let (sig, abi, env) = match fn_type.sty {
-        ty::TyFnDef(_, _, f) |
-        ty::TyFnPtr(f) => {
-            (&f.sig, f.abi, None)
-        }
-        ty::TyClosure(closure_did, ref substs) => {
-            let infcx = infer::normalizing_infer_ctxt(ccx.tcx(),
-                                                      &ccx.tcx().tables,
-                                                      ProjectionMode::Any);
-            function_type = infcx.closure_type(closure_did, substs);
-            let self_type = base::self_type_for_closure(ccx, closure_did, fn_type);
-            debug!("declare_rust_fn function_type={:?} self_type={:?}",
-                   function_type, self_type);
-            (&function_type.sig, Abi::RustCall, Some(self_type))
-        }
-        _ => ccx.sess().bug("expected closure or fn")
+    let f = match fn_type.sty {
+        ty::TyFnDef(_, _, f) | ty::TyFnPtr(f) => f,
+        _ => unreachable!("expected fn type for {:?}, found {:?}", name, fn_type)
     };
 
-
-    let sig = ccx.tcx().erase_late_bound_regions(sig);
+    let sig = ccx.tcx().erase_late_bound_regions(&f.sig);
     let sig = infer::normalize_associated_type(ccx.tcx(), &sig);
     debug!("declare_rust_fn (after region erasure) sig={:?}", sig);
 
-    let (cconv, llfty) = if abi == Abi::Rust || abi == Abi::RustCall {
-        (llvm::CCallConv, type_of::type_of_rust_fn(ccx, env, &sig, abi))
+    let (cconv, llfty) = if f.abi == Abi::Rust || f.abi == Abi::RustCall {
+        (llvm::CCallConv, type_of::type_of_rust_fn(ccx, &sig, f.abi))
     } else {
-        let fty = FnType::new(ccx, abi, &sig, &[]);
+        let fty = FnType::new(ccx, f.abi, &sig, &[]);
         (fty.cconv, fty.to_llvm(ccx))
     };
 
@@ -137,10 +119,10 @@ pub fn declare_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, name: &str,
         llvm::SetFunctionAttribute(llfn, llvm::Attribute::NoReturn);
     }
 
-    if abi == Abi::Rust || abi == Abi::RustCall {
+    if f.abi == Abi::Rust || f.abi == Abi::RustCall {
         attributes::from_fn_type(ccx, fn_type).apply_llfn(llfn);
     } else {
-        FnType::new(ccx, abi, &sig, &[]).add_attributes(llfn);
+        FnType::new(ccx, f.abi, &sig, &[]).add_attributes(llfn);
     }
 
     llfn
diff --git a/src/librustc_trans/trans/type_of.rs b/src/librustc_trans/trans/type_of.rs
index b3beecfb9b8d..b4f431f09e8c 100644
--- a/src/librustc_trans/trans/type_of.rs
+++ b/src/librustc_trans/trans/type_of.rs
@@ -88,14 +88,11 @@ pub fn untuple_arguments<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
 }
 
 pub fn type_of_rust_fn<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
-                                 maybe_env: Option<Ty<'tcx>>,
                                  sig: &ty::FnSig<'tcx>,
                                  abi: Abi)
                                  -> Type
 {
-    debug!("type_of_rust_fn(sig={:?},abi={:?})",
-           sig,
-           abi);
+    debug!("type_of_rust_fn(sig={:?}, abi={:?})", sig, abi);
 
     assert!(!sig.variadic); // rust fns are never variadic
 
@@ -129,11 +126,6 @@ pub fn type_of_rust_fn<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
         ty::FnDiverging => Type::void(cx)
     };
 
-    // Arg 1: Environment
-    if let Some(env_ty) = maybe_env {
-        atys.push(type_of_explicit_arg(cx, env_ty));
-    }
-
     // ... then explicit args.
     for input in inputs {
         let arg_ty = type_of_explicit_arg(cx, input);
@@ -384,7 +376,7 @@ pub fn in_memory_type_of<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) ->
         let sig = cx.tcx().erase_late_bound_regions(&f.sig);
         let sig = infer::normalize_associated_type(cx.tcx(), &sig);
         if f.abi == Abi::Rust || f.abi == Abi::RustCall {
-            type_of_rust_fn(cx, None, &sig, f.abi).ptr_to()
+            type_of_rust_fn(cx, &sig, f.abi).ptr_to()
         } else {
             FnType::new(cx, f.abi, &sig, &[]).to_llvm(cx).ptr_to()
         }