diff --git a/src/librustc/arena.rs b/src/librustc/arena.rs
index a24ef9523d41..53349773a360 100644
--- a/src/librustc/arena.rs
+++ b/src/librustc/arena.rs
@@ -91,6 +91,8 @@ macro_rules! arena_types {
                 rustc::hir::def_id::DefId,
                 String
             >,
+            [few] get_lib_features: rustc::middle::lib_features::LibFeatures,
+            [few] defined_lib_features: rustc::middle::lang_items::LanguageItems,
         ], $tcx);
     )
 }
diff --git a/src/librustc/middle/cstore.rs b/src/librustc/middle/cstore.rs
index d22de6c64769..6f9abcd624f9 100644
--- a/src/librustc/middle/cstore.rs
+++ b/src/librustc/middle/cstore.rs
@@ -256,8 +256,8 @@ pub fn used_crates(tcx: TyCtxt<'_, '_, '_>, prefer: LinkagePreference)
             Some((cnum, path))
         })
         .collect::<Vec<_>>();
-    let mut ordering = tcx.postorder_cnums(LOCAL_CRATE);
-    Lrc::make_mut(&mut ordering).reverse();
+    let mut ordering = tcx.postorder_cnums(LOCAL_CRATE).to_owned();
+    ordering.reverse();
     libs.sort_by_cached_key(|&(a, _)| {
         ordering.iter().position(|x| *x == a)
     });
diff --git a/src/librustc/middle/stability.rs b/src/librustc/middle/stability.rs
index abcf164cda6d..ac0e99137cbc 100644
--- a/src/librustc/middle/stability.rs
+++ b/src/librustc/middle/stability.rs
@@ -883,7 +883,7 @@ pub fn check_unused_or_stable_features<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
     remaining_lib_features.remove(&Symbol::intern("test"));
 
     let check_features =
-        |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &Vec<_>| {
+        |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &[_]| {
             for &(feature, since) in defined_features {
                 if let Some(since) = since {
                     if let Some(span) = remaining_lib_features.get(&feature) {
@@ -908,7 +908,7 @@ pub fn check_unused_or_stable_features<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
             if remaining_lib_features.is_empty() {
                 break;
             }
-            check_features(&mut remaining_lib_features, &tcx.defined_lib_features(cnum));
+            check_features(&mut remaining_lib_features, tcx.defined_lib_features(cnum));
         }
     }
 
diff --git a/src/librustc/query/mod.rs b/src/librustc/query/mod.rs
index ae4e22e6e490..84e88acbbded 100644
--- a/src/librustc/query/mod.rs
+++ b/src/librustc/query/mod.rs
@@ -787,22 +787,22 @@ rustc_queries! {
         query item_children(_: DefId) -> &'tcx [Export<hir::HirId>] {}
         query extern_mod_stmt_cnum(_: DefId) -> Option<CrateNum> {}
 
-        query get_lib_features(_: CrateNum) -> Lrc<LibFeatures> {
+        query get_lib_features(_: CrateNum) -> &'tcx LibFeatures {
             eval_always
             desc { "calculating the lib features map" }
         }
         query defined_lib_features(_: CrateNum)
-            -> Lrc<Vec<(Symbol, Option<Symbol>)>> {
+            -> &'tcx [(Symbol, Option<Symbol>)] {
             desc { "calculating the lib features defined in a crate" }
         }
-        query get_lang_items(_: CrateNum) -> Lrc<LanguageItems> {
+        query get_lang_items(_: CrateNum) -> &'tcx LanguageItems {
             eval_always
             desc { "calculating the lang items map" }
         }
-        query defined_lang_items(_: CrateNum) -> Lrc<Vec<(DefId, usize)>> {
+        query defined_lang_items(_: CrateNum) -> &'tcx [(DefId, usize)] {
             desc { "calculating the lang items defined in a crate" }
         }
-        query missing_lang_items(_: CrateNum) -> Lrc<Vec<LangItem>> {
+        query missing_lang_items(_: CrateNum) -> &'tcx [LangItem] {
             desc { "calculating the missing lang items in a crate" }
         }
         query visible_parent_map(_: CrateNum)
@@ -817,7 +817,7 @@ rustc_queries! {
             eval_always
             desc { "looking at the source for a crate" }
         }
-        query postorder_cnums(_: CrateNum) -> Lrc<Vec<CrateNum>> {
+        query postorder_cnums(_: CrateNum) -> &'tcx [CrateNum] {
             eval_always
             desc { "generating a postorder list of CrateNums" }
         }
@@ -829,7 +829,7 @@ rustc_queries! {
             eval_always
         }
         query maybe_unused_extern_crates(_: CrateNum)
-            -> Lrc<Vec<(DefId, Span)>> {
+            -> &'tcx [(DefId, Span)] {
             eval_always
             desc { "looking up all possibly unused extern crates" }
         }
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index 87f6f9f070ed..d83b2ce842a8 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -1376,11 +1376,11 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         self.sess.consider_optimizing(&cname, msg)
     }
 
-    pub fn lib_features(self) -> Lrc<middle::lib_features::LibFeatures> {
+    pub fn lib_features(self) -> &'gcx middle::lib_features::LibFeatures {
         self.get_lib_features(LOCAL_CRATE)
     }
 
-    pub fn lang_items(self) -> Lrc<middle::lang_items::LanguageItems> {
+    pub fn lang_items(self) -> &'gcx middle::lang_items::LanguageItems {
         self.get_lang_items(LOCAL_CRATE)
     }
 
@@ -3060,11 +3060,11 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
     };
     providers.get_lib_features = |tcx, id| {
         assert_eq!(id, LOCAL_CRATE);
-        Lrc::new(middle::lib_features::collect(tcx))
+        tcx.arena.alloc(middle::lib_features::collect(tcx))
     };
     providers.get_lang_items = |tcx, id| {
         assert_eq!(id, LOCAL_CRATE);
-        Lrc::new(middle::lang_items::collect(tcx))
+        tcx.arena.alloc(middle::lang_items::collect(tcx))
     };
     providers.upvars = |tcx, id| tcx.gcx.upvars.get(&id).map(|v| &v[..]);
     providers.maybe_unused_trait_import = |tcx, id| {
@@ -3072,7 +3072,7 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
     };
     providers.maybe_unused_extern_crates = |tcx, cnum| {
         assert_eq!(cnum, LOCAL_CRATE);
-        Lrc::new(tcx.maybe_unused_extern_crates.clone())
+        &tcx.maybe_unused_extern_crates[..]
     };
     providers.names_imported_by_glob_use = |tcx, id| {
         assert_eq!(id.krate, LOCAL_CRATE);
@@ -3103,7 +3103,7 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
     };
     providers.postorder_cnums = |tcx, cnum| {
         assert_eq!(cnum, LOCAL_CRATE);
-        Lrc::new(tcx.cstore.postorder_cnums_untracked())
+        tcx.arena.alloc_slice(&tcx.cstore.postorder_cnums_untracked())
     };
     providers.output_filenames = |tcx, cnum| {
         assert_eq!(cnum, LOCAL_CRATE);
diff --git a/src/librustc_metadata/cstore_impl.rs b/src/librustc_metadata/cstore_impl.rs
index bdb29006a0e0..2469732a749d 100644
--- a/src/librustc_metadata/cstore_impl.rs
+++ b/src/librustc_metadata/cstore_impl.rs
@@ -229,9 +229,9 @@ provide! { <'tcx> tcx, def_id, other, cdata,
         cdata.each_child_of_item(def_id.index, |child| result.push(child), tcx.sess);
         tcx.arena.alloc_slice(&result)
     }
-    defined_lib_features => { Lrc::new(cdata.get_lib_features()) }
-    defined_lang_items => { Lrc::new(cdata.get_lang_items()) }
-    missing_lang_items => { Lrc::new(cdata.get_missing_lang_items()) }
+    defined_lib_features => { cdata.get_lib_features(tcx) }
+    defined_lang_items => { cdata.get_lang_items(tcx) }
+    missing_lang_items => { cdata.get_missing_lang_items(tcx) }
 
     missing_extern_crate_item => {
         let r = match *cdata.extern_crate.borrow() {
diff --git a/src/librustc_metadata/decoder.rs b/src/librustc_metadata/decoder.rs
index c4037dcfac0a..ea79161a6d90 100644
--- a/src/librustc_metadata/decoder.rs
+++ b/src/librustc_metadata/decoder.rs
@@ -708,26 +708,30 @@ impl<'a, 'tcx> CrateMetadata {
     }
 
     /// Iterates over all the stability attributes in the given crate.
-    pub fn get_lib_features(&self) -> Vec<(ast::Name, Option<ast::Name>)> {
+    pub fn get_lib_features(
+        &self,
+        tcx: TyCtxt<'_, 'tcx, '_>,
+    ) -> &'tcx [(ast::Name, Option<ast::Name>)] {
         // FIXME: For a proc macro crate, not sure whether we should return the "host"
         // features or an empty Vec. Both don't cause ICEs.
-        self.root
+        tcx.arena.alloc_from_iter(self.root
             .lib_features
-            .decode(self)
-            .collect()
+            .decode(self))
     }
 
     /// Iterates over the language items in the given crate.
-    pub fn get_lang_items(&self) -> Vec<(DefId, usize)> {
+    pub fn get_lang_items(
+        &self,
+        tcx: TyCtxt<'_, 'tcx, '_>,
+    ) -> &'tcx [(DefId, usize)] {
         if self.proc_macros.is_some() {
             // Proc macro crates do not export any lang-items to the target.
-            vec![]
+            &[]
         } else {
-            self.root
+            tcx.arena.alloc_from_iter(self.root
                 .lang_items
                 .decode(self)
-                .map(|(def_index, index)| (self.local_def_id(def_index), index))
-                .collect()
+                .map(|(def_index, index)| (self.local_def_id(def_index), index)))
         }
     }
 
@@ -1102,15 +1106,17 @@ impl<'a, 'tcx> CrateMetadata {
             .collect()
     }
 
-    pub fn get_missing_lang_items(&self) -> Vec<lang_items::LangItem> {
+    pub fn get_missing_lang_items(
+        &self,
+        tcx: TyCtxt<'_, 'tcx, '_>,
+    ) -> &'tcx [lang_items::LangItem] {
         if self.proc_macros.is_some() {
             // Proc macro crates do not depend on any target weak lang-items.
-            vec![]
+            &[]
         } else {
-            self.root
+            tcx.arena.alloc_from_iter(self.root
                 .lang_items_missing
-                .decode(self)
-                .collect()
+                .decode(self))
         }
     }