diff --git a/src/bootstrap/bin/rustc.rs b/src/bootstrap/bin/rustc.rs
index 62b7f6cb72e3b..906c468241ae9 100644
--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -194,6 +194,8 @@ fn main() {
                 // do that we pass a weird flag to the compiler to get it to do
                 // so. Note that this is definitely a hack, and we should likely
                 // flesh out rpath support more fully in the future.
+                //
+                // FIXME: remove condition after next stage0
                 if stage != "0" {
                     cmd.arg("-Z").arg("osx-rpath-install-name");
                 }
@@ -218,6 +220,17 @@ fn main() {
             cmd.arg("-Z").arg("unstable-options");
             cmd.arg("-C").arg("target-feature=+crt-static");
         }
+
+        // Force all crates compiled by this compiler to (a) be unstable and (b)
+        // allow the `rustc_private` feature to link to other unstable crates
+        // also in the sysroot.
+        //
+        // FIXME: remove condition after next stage0
+        if env::var_os("RUSTC_FORCE_UNSTABLE").is_some() {
+            if stage != "0" {
+                cmd.arg("-Z").arg("force-unstable-if-unmarked");
+            }
+        }
     }
 
     if verbose > 1 {
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 017d4015134d0..ea0b521a2ce69 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -479,7 +479,8 @@ impl Build {
         // compiled with debuginfo.
         if mode != Mode::Tool {
              cargo.env("RUSTC_DEBUGINFO", self.config.rust_debuginfo.to_string())
-                  .env("RUSTC_DEBUGINFO_LINES", self.config.rust_debuginfo_lines.to_string());
+                  .env("RUSTC_DEBUGINFO_LINES", self.config.rust_debuginfo_lines.to_string())
+                  .env("RUSTC_FORCE_UNSTABLE", "1");
         }
 
         // Enable usage of unstable features
@@ -524,7 +525,9 @@ impl Build {
         // the comipiler, libs, and tests are stable and we don't want to make
         // their deps unstable (since this would break the first invariant
         // above).
-        if mode != Mode::Tool {
+        //
+        // FIXME: remove this after next stage0
+        if mode != Mode::Tool && stage == 0 {
             cargo.env("RUSTBUILD_UNSTABLE", "1");
         }
 
diff --git a/src/libarena/lib.rs b/src/libarena/lib.rs
index 321fa2edd56c7..c4c1635aa2a5a 100644
--- a/src/libarena/lib.rs
+++ b/src/libarena/lib.rs
@@ -19,7 +19,7 @@
 //! objects of a single type.
 
 #![crate_name = "arena"]
-#![unstable(feature = "rustc_private", issue = "27812")]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -32,7 +32,7 @@
 #![feature(core_intrinsics)]
 #![feature(dropck_eyepatch)]
 #![feature(generic_param_attrs)]
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![cfg_attr(test, feature(test))]
 
 #![allow(deprecated)]
diff --git a/src/libflate/lib.rs b/src/libflate/lib.rs
index 3619be82829ca..e0bea884f31c5 100644
--- a/src/libflate/lib.rs
+++ b/src/libflate/lib.rs
@@ -15,7 +15,7 @@
 //! [mz]: https://code.google.com/p/miniz/
 
 #![crate_name = "flate"]
-#![unstable(feature = "rustc_private", issue = "27812")]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -25,7 +25,7 @@
 #![deny(warnings)]
 
 #![feature(libc)]
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![feature(unique)]
 #![cfg_attr(test, feature(rand))]
 
diff --git a/src/libfmt_macros/lib.rs b/src/libfmt_macros/lib.rs
index f5a687de64e48..641a42b08188f 100644
--- a/src/libfmt_macros/lib.rs
+++ b/src/libfmt_macros/lib.rs
@@ -15,7 +15,7 @@
 //! generated instead.
 
 #![crate_name = "fmt_macros"]
-#![unstable(feature = "rustc_private", issue = "27812")]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -25,7 +25,7 @@
        test(attr(deny(warnings))))]
 #![deny(warnings)]
 
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![feature(unicode)]
 
 pub use self::Piece::*;
diff --git a/src/libgetopts/lib.rs b/src/libgetopts/lib.rs
index a5cd9fab2cf4b..c69c68ba59c01 100644
--- a/src/libgetopts/lib.rs
+++ b/src/libgetopts/lib.rs
@@ -78,9 +78,9 @@
 //! ```
 
 #![crate_name = "getopts"]
-#![unstable(feature = "rustc_private",
+#![cfg_attr(stage0, unstable(feature = "rustc_private",
             reason = "use the crates.io `getopts` library instead",
-            issue = "27812")]
+            issue = "27812"))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -91,7 +91,7 @@
 
 #![deny(missing_docs)]
 #![deny(warnings)]
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 
 use self::Name::*;
 use self::HasArg::*;
diff --git a/src/libgraphviz/lib.rs b/src/libgraphviz/lib.rs
index 1b2c7775185f7..2c6744e7c9053 100644
--- a/src/libgraphviz/lib.rs
+++ b/src/libgraphviz/lib.rs
@@ -284,8 +284,8 @@
 //! * [DOT language](http://www.graphviz.org/doc/info/lang.html)
 
 #![crate_name = "graphviz"]
-#![unstable(feature = "rustc_private", issue = "27812")]
-#![feature(staged_api)]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(staged_api))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
diff --git a/src/libproc_macro_plugin/lib.rs b/src/libproc_macro_plugin/lib.rs
index a6dad64125331..68c5d49591839 100644
--- a/src/libproc_macro_plugin/lib.rs
+++ b/src/libproc_macro_plugin/lib.rs
@@ -72,7 +72,7 @@
 //! }
 //! ```
 #![crate_name = "proc_macro_plugin"]
-#![unstable(feature = "rustc_private", issue = "27812")]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
 #![feature(plugin_registrar)]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
@@ -81,9 +81,9 @@
        html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
+#![cfg_attr(stage0, feature(rustc_private))]
 
 extern crate rustc_plugin;
 extern crate syntax;
diff --git a/src/librustc/lib.rs b/src/librustc/lib.rs
index d3954326e7b72..5cf26ea8bfca5 100644
--- a/src/librustc/lib.rs
+++ b/src/librustc/lib.rs
@@ -15,7 +15,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "rustc"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -36,15 +35,17 @@
 #![feature(nonzero)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
 #![feature(slice_patterns)]
 #![feature(specialization)]
-#![feature(staged_api)]
 #![feature(unboxed_closures)]
 #![feature(discriminant_value)]
 #![feature(sort_unstable)]
 #![feature(trace_macros)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 #![recursion_limit="128"]
 
 extern crate arena;
diff --git a/src/librustc/middle/cstore.rs b/src/librustc/middle/cstore.rs
index da899a9130c8b..569b1aeeb09d7 100644
--- a/src/librustc/middle/cstore.rs
+++ b/src/librustc/middle/cstore.rs
@@ -233,7 +233,6 @@ pub trait CrateStore {
     fn export_macros(&self, cnum: CrateNum);
     fn lang_items(&self, cnum: CrateNum) -> Vec<(DefIndex, usize)>;
     fn missing_lang_items(&self, cnum: CrateNum) -> Vec<lang_items::LangItem>;
-    fn is_staged_api(&self, cnum: CrateNum) -> bool;
     fn is_allocator(&self, cnum: CrateNum) -> bool;
     fn is_panic_runtime(&self, cnum: CrateNum) -> bool;
     fn is_compiler_builtins(&self, cnum: CrateNum) -> bool;
@@ -356,7 +355,6 @@ impl CrateStore for DummyCrateStore {
         { bug!("lang_items") }
     fn missing_lang_items(&self, cnum: CrateNum) -> Vec<lang_items::LangItem>
         { bug!("missing_lang_items") }
-    fn is_staged_api(&self, cnum: CrateNum) -> bool { bug!("is_staged_api") }
     fn dep_kind(&self, cnum: CrateNum) -> DepKind { bug!("is_explicitly_linked") }
     fn export_macros(&self, cnum: CrateNum) { bug!("export_macros") }
     fn is_allocator(&self, cnum: CrateNum) -> bool { bug!("is_allocator") }
diff --git a/src/librustc/middle/stability.rs b/src/librustc/middle/stability.rs
index 198f7420f5d2b..d74877e355a79 100644
--- a/src/librustc/middle/stability.rs
+++ b/src/librustc/middle/stability.rs
@@ -13,12 +13,12 @@
 
 pub use self::StabilityLevel::*;
 
-use hir::map as hir_map;
 use lint;
 use hir::def::Def;
 use hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefId, DefIndex, LOCAL_CRATE};
 use ty::{self, TyCtxt};
 use middle::privacy::AccessLevels;
+use session::Session;
 use syntax::symbol::Symbol;
 use syntax_pos::{Span, DUMMY_SP};
 use syntax::ast;
@@ -123,7 +123,7 @@ impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
                    item_sp: Span, kind: AnnotationKind, visit_children: F)
         where F: FnOnce(&mut Self)
     {
-        if self.index.staged_api[&LOCAL_CRATE] && self.tcx.sess.features.borrow().staged_api {
+        if self.index.staged_api[&LOCAL_CRATE] {
             debug!("annotate(id = {:?}, attrs = {:?})", id, attrs);
             if let Some(..) = attr::find_deprecation(self.tcx.sess.diagnostic(), attrs, item_sp) {
                 self.tcx.sess.span_err(item_sp, "`#[deprecated]` cannot be used in staged api, \
@@ -390,20 +390,36 @@ impl<'a, 'tcx> Index<'tcx> {
             parent_depr: None,
             in_trait_impl: false,
         };
+
+        // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
+        // a parent stability annotation which indicates that this is private
+        // with the `rustc_private` feature. This is intended for use when
+        // compiling librustc crates themselves so we can leverage crates.io
+        // while maintaining the invariant that all sysroot crates are unstable
+        // by default and are unable to be used.
+        if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
+            let reason = "this crate is being loaded from the sysroot, and \
+                          unstable location; did you mean to load this crate \
+                          from crates.io via `Cargo.toml` instead?";
+            let stability = tcx.intern_stability(Stability {
+                level: attr::StabilityLevel::Unstable {
+                    reason: Some(Symbol::intern(reason)),
+                    issue: 27812,
+                },
+                feature: Symbol::intern("rustc_private"),
+                rustc_depr: None,
+            });
+            annotator.parent_stab = Some(stability);
+        }
+
         annotator.annotate(ast::CRATE_NODE_ID, &krate.attrs, krate.span, AnnotationKind::Required,
                            |v| intravisit::walk_crate(v, krate));
     }
 
-    pub fn new(hir_map: &hir_map::Map) -> Index<'tcx> {
-        let krate = hir_map.krate();
-
-        let mut is_staged_api = false;
-        for attr in &krate.attrs {
-            if attr.path == "stable" || attr.path == "unstable" {
-                is_staged_api = true;
-                break
-            }
-        }
+    pub fn new(sess: &Session) -> Index<'tcx> {
+        let is_staged_api =
+            sess.opts.debugging_opts.force_unstable_if_unmarked ||
+            sess.features.borrow().staged_api;
 
         let mut staged_api = FxHashMap();
         staged_api.insert(LOCAL_CRATE, is_staged_api);
@@ -496,8 +512,10 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             }
         }
 
-        let is_staged_api = *self.stability.borrow_mut().staged_api.entry(def_id.krate)
-            .or_insert_with(|| self.sess.cstore.is_staged_api(def_id.krate));
+        let is_staged_api = self.lookup_stability(DefId {
+            index: CRATE_DEF_INDEX,
+            ..def_id
+        }).is_some();
         if !is_staged_api {
             return;
         }
@@ -530,15 +548,32 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
         match stability {
             Some(&Stability { level: attr::Unstable {ref reason, issue}, ref feature, .. }) => {
-                if !self.stability.borrow().active_features.contains(feature) {
-                    let msg = match *reason {
-                        Some(ref r) => format!("use of unstable library feature '{}': {}",
-                                               feature.as_str(), &r),
-                        None => format!("use of unstable library feature '{}'", &feature)
-                    };
-                    emit_feature_err(&self.sess.parse_sess, &feature.as_str(), span,
-                                     GateIssue::Library(Some(issue)), &msg);
+                if self.stability.borrow().active_features.contains(feature) {
+                    return
                 }
+
+                // When we're compiling the compiler itself we may pull in
+                // crates from crates.io, but those crates may depend on other
+                // crates also pulled in from crates.io. We want to ideally be
+                // able to compile everything without requiring upstream
+                // modifications, so in the case that this looks like a
+                // rustc_private crate (e.g. a compiler crate) and we also have
+                // the `-Z force-unstable-if-unmarked` flag present (we're
+                // compiling a compiler crate), then let this missing feature
+                // annotation slide.
+                if *feature == "rustc_private" && issue == 27812 {
+                    if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
+                        return
+                    }
+                }
+
+                let msg = match *reason {
+                    Some(ref r) => format!("use of unstable library feature '{}': {}",
+                                           feature.as_str(), &r),
+                    None => format!("use of unstable library feature '{}'", &feature)
+                };
+                emit_feature_err(&self.sess.parse_sess, &feature.as_str(), span,
+                                 GateIssue::Library(Some(issue)), &msg);
             }
             Some(_) => {
                 // Stable APIs are always ok to call and deprecated APIs are
@@ -658,7 +693,7 @@ pub fn check_unused_or_stable_features<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
 
     let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
 
-    if tcx.stability.borrow().staged_api[&LOCAL_CRATE] && tcx.sess.features.borrow().staged_api {
+    if tcx.stability.borrow().staged_api[&LOCAL_CRATE] {
         let krate = tcx.hir.krate();
         let mut missing = MissingStabilityAnnotations {
             tcx: tcx,
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 75bc940625d82..884a71f0d32d4 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -1027,6 +1027,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "add a source pattern to the file path remapping config"),
     remap_path_prefix_to: Vec<String> = (vec![], parse_string_push, [TRACKED],
         "add a mapping target to the file path remapping config"),
+    force_unstable_if_unmarked: bool = (false, parse_bool, [TRACKED],
+        "force all crates to be `rustc_private` unstable"),
 }
 
 pub fn default_lib_output() -> CrateType {
diff --git a/src/librustc_back/lib.rs b/src/librustc_back/lib.rs
index 6679cc73029c7..69eabfe2ac0bf 100644
--- a/src/librustc_back/lib.rs
+++ b/src/librustc_back/lib.rs
@@ -22,7 +22,6 @@
 //! build speedups.
 
 #![crate_name = "rustc_back"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -34,10 +33,12 @@
 #![feature(const_fn)]
 #![feature(libc)]
 #![feature(rand)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![cfg_attr(test, feature(rand))]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 extern crate syntax;
 extern crate libc;
 extern crate serialize;
diff --git a/src/librustc_bitflags/lib.rs b/src/librustc_bitflags/lib.rs
index edd474b2e9edc..23558d8288342 100644
--- a/src/librustc_bitflags/lib.rs
+++ b/src/librustc_bitflags/lib.rs
@@ -11,11 +11,11 @@
 
 #![crate_name = "rustc_bitflags"]
 #![feature(associated_consts)]
-#![feature(staged_api)]
 #![crate_type = "rlib"]
 #![no_std]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![deny(warnings)]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 //! A typesafe bitmask flag generator.
 
diff --git a/src/librustc_borrowck/lib.rs b/src/librustc_borrowck/lib.rs
index a1d3357faf566..617326808970b 100644
--- a/src/librustc_borrowck/lib.rs
+++ b/src/librustc_borrowck/lib.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![crate_name = "rustc_borrowck"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -21,10 +20,13 @@
 
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![feature(associated_consts)]
 #![feature(nonzero)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 #[macro_use] extern crate log;
 #[macro_use] extern crate syntax;
 extern crate syntax_pos;
diff --git a/src/librustc_const_eval/lib.rs b/src/librustc_const_eval/lib.rs
index fa3161a860498..8142829e81601 100644
--- a/src/librustc_const_eval/lib.rs
+++ b/src/librustc_const_eval/lib.rs
@@ -15,7 +15,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "rustc_const_eval"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -23,8 +22,6 @@
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(slice_patterns)]
 #![feature(box_patterns)]
@@ -32,6 +29,10 @@
 #![feature(const_fn)]
 #![feature(i128_type)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 extern crate arena;
 #[macro_use] extern crate syntax;
 #[macro_use] extern crate log;
diff --git a/src/librustc_const_math/lib.rs b/src/librustc_const_math/lib.rs
index b7833a5440321..528170781ea75 100644
--- a/src/librustc_const_math/lib.rs
+++ b/src/librustc_const_math/lib.rs
@@ -15,7 +15,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "rustc_const_math"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -23,12 +22,14 @@
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![feature(const_fn)]
 #![feature(i128)]
 #![feature(i128_type)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 extern crate syntax;
 
 extern crate serialize as rustc_serialize; // used by deriving
diff --git a/src/librustc_data_structures/lib.rs b/src/librustc_data_structures/lib.rs
index 00c46d992bfd5..c254dfc48d225 100644
--- a/src/librustc_data_structures/lib.rs
+++ b/src/librustc_data_structures/lib.rs
@@ -17,7 +17,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "rustc_data_structures"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -28,8 +27,6 @@
 #![feature(shared)]
 #![feature(collections_range)]
 #![feature(nonzero)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![feature(unboxed_closures)]
 #![feature(fn_traits)]
 #![feature(untagged_unions)]
@@ -42,6 +39,10 @@
 #![feature(manually_drop)]
 #![feature(struct_field_attributes)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 #![cfg_attr(unix, feature(libc))]
 #![cfg_attr(test, feature(test))]
 
diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs
index 5f14890665cab..8fddbe110b0e6 100644
--- a/src/librustc_driver/driver.rs
+++ b/src/librustc_driver/driver.rs
@@ -882,7 +882,7 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
               "static item recursion checking",
               || static_recursion::check_crate(sess, &hir_map))?;
 
-    let index = stability::Index::new(&hir_map);
+    let index = stability::Index::new(&sess);
 
     let mut local_providers = ty::maps::Providers::default();
     borrowck::provide(&mut local_providers);
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index eef3b38a8b5e9..024fc546a158e 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -15,7 +15,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "rustc_driver"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -28,9 +27,11 @@
 #![feature(libc)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
 #![feature(set_stdio)]
-#![feature(staged_api)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 extern crate arena;
 extern crate getopts;
diff --git a/src/librustc_driver/test.rs b/src/librustc_driver/test.rs
index 8b95be00fa752..3b4f2560fc555 100644
--- a/src/librustc_driver/test.rs
+++ b/src/librustc_driver/test.rs
@@ -138,7 +138,7 @@ fn test_env<F>(source_string: &str,
     // run just enough stuff to build a tcx:
     let lang_items = lang_items::collect_language_items(&sess, &hir_map);
     let named_region_map = resolve_lifetime::krate(&sess, &hir_map);
-    let index = stability::Index::new(&hir_map);
+    let index = stability::Index::new(&sess);
     TyCtxt::create_and_enter(&sess,
                              ty::maps::Providers::default(),
                              ty::maps::Providers::default(),
diff --git a/src/librustc_errors/lib.rs b/src/librustc_errors/lib.rs
index db8c9ac306bba..0f2e1669a47ad 100644
--- a/src/librustc_errors/lib.rs
+++ b/src/librustc_errors/lib.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![crate_name = "rustc_errors"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -19,11 +18,13 @@
 
 #![feature(custom_attribute)]
 #![allow(unused_attributes)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![feature(range_contains)]
 #![feature(libc)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 extern crate term;
 extern crate libc;
 extern crate serialize as rustc_serialize;
diff --git a/src/librustc_incremental/lib.rs b/src/librustc_incremental/lib.rs
index 95f0a96fdf965..70f967d50b0e1 100644
--- a/src/librustc_incremental/lib.rs
+++ b/src/librustc_incremental/lib.rs
@@ -11,7 +11,6 @@
 //! Support for serializing the dep-graph and reloading it.
 
 #![crate_name = "rustc_incremental"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -19,12 +18,14 @@
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![feature(rand)]
 #![feature(conservative_impl_trait)]
 #![feature(sort_unstable)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 extern crate graphviz;
 #[macro_use] extern crate rustc;
 extern crate rustc_data_structures;
diff --git a/src/librustc_lint/lib.rs b/src/librustc_lint/lib.rs
index 53ea3a8333f2d..2d0b5a6a51c6b 100644
--- a/src/librustc_lint/lib.rs
+++ b/src/librustc_lint/lib.rs
@@ -20,7 +20,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "rustc_lint"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -34,9 +33,11 @@
 #![feature(i128_type)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
 #![feature(slice_patterns)]
-#![feature(staged_api)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 #[macro_use]
 extern crate syntax;
diff --git a/src/librustc_llvm/lib.rs b/src/librustc_llvm/lib.rs
index c9b3a7ff3f3aa..790d493f1914c 100644
--- a/src/librustc_llvm/lib.rs
+++ b/src/librustc_llvm/lib.rs
@@ -14,7 +14,6 @@
 #![allow(dead_code)]
 
 #![crate_name = "rustc_llvm"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -27,10 +26,12 @@
 #![feature(concat_idents)]
 #![feature(libc)]
 #![feature(link_args)]
-#![feature(staged_api)]
-#![feature(rustc_private)]
 #![feature(static_nobundle)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 extern crate libc;
 #[macro_use]
 #[no_link]
diff --git a/src/librustc_metadata/cstore.rs b/src/librustc_metadata/cstore.rs
index 8d53e7d49ee81..c12b4209675de 100644
--- a/src/librustc_metadata/cstore.rs
+++ b/src/librustc_metadata/cstore.rs
@@ -269,15 +269,6 @@ impl CrateMetadata {
         self.root.disambiguator
     }
 
-    pub fn is_staged_api(&self, dep_graph: &DepGraph) -> bool {
-        for attr in self.get_item_attrs(CRATE_DEF_INDEX, dep_graph).iter() {
-            if attr.path == "stable" || attr.path == "unstable" {
-                return true;
-            }
-        }
-        false
-    }
-
     pub fn is_allocator(&self, dep_graph: &DepGraph) -> bool {
         let attrs = self.get_item_attrs(CRATE_DEF_INDEX, dep_graph);
         attr::contains_name(&attrs, "allocator")
diff --git a/src/librustc_metadata/cstore_impl.rs b/src/librustc_metadata/cstore_impl.rs
index f3fb427fed66f..dbf3e94832fc4 100644
--- a/src/librustc_metadata/cstore_impl.rs
+++ b/src/librustc_metadata/cstore_impl.rs
@@ -229,11 +229,6 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(cnum).get_missing_lang_items(&self.dep_graph)
     }
 
-    fn is_staged_api(&self, cnum: CrateNum) -> bool
-    {
-        self.get_crate_data(cnum).is_staged_api(&self.dep_graph)
-    }
-
     fn is_allocator(&self, cnum: CrateNum) -> bool
     {
         self.get_crate_data(cnum).is_allocator(&self.dep_graph)
diff --git a/src/librustc_metadata/lib.rs b/src/librustc_metadata/lib.rs
index 90eb2bc0f6a7d..27555f49e57fc 100644
--- a/src/librustc_metadata/lib.rs
+++ b/src/librustc_metadata/lib.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![crate_name = "rustc_metadata"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -24,10 +23,12 @@
 #![feature(proc_macro_internals)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
 #![feature(specialization)]
-#![feature(staged_api)]
 #![feature(discriminant_value)]
+#![feature(rustc_private)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 #[macro_use]
 extern crate log;
diff --git a/src/librustc_mir/lib.rs b/src/librustc_mir/lib.rs
index 5fa56bac1379b..014705bf32fa8 100644
--- a/src/librustc_mir/lib.rs
+++ b/src/librustc_mir/lib.rs
@@ -18,18 +18,19 @@ Rust MIR: a lowered representation of Rust. Also: an experiment!
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![deny(warnings)]
-#![unstable(feature = "rustc_private", issue = "27812")]
 
 #![feature(associated_consts)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(i128_type)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![feature(placement_in_syntax)]
 #![feature(collection_placement)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 #[macro_use] extern crate log;
 extern crate graphviz as dot;
 #[macro_use]
diff --git a/src/librustc_passes/lib.rs b/src/librustc_passes/lib.rs
index 22566c813d86a..97f0022b8db8d 100644
--- a/src/librustc_passes/lib.rs
+++ b/src/librustc_passes/lib.rs
@@ -15,7 +15,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "rustc_passes"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -24,8 +23,10 @@
 #![deny(warnings)]
 
 #![feature(rustc_diagnostic_macros)]
-#![feature(staged_api)]
-#![feature(rustc_private)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 #[macro_use]
 extern crate rustc;
diff --git a/src/librustc_platform_intrinsics/lib.rs b/src/librustc_platform_intrinsics/lib.rs
index dd2d60a1d22d6..21dd360c9bb74 100644
--- a/src/librustc_platform_intrinsics/lib.rs
+++ b/src/librustc_platform_intrinsics/lib.rs
@@ -9,10 +9,10 @@
 // except according to those terms.
 
 #![crate_name = "rustc_platform_intrinsics"]
-#![unstable(feature = "rustc_private", issue = "27812")]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![deny(warnings)]
 #![allow(bad_style)]
 
diff --git a/src/librustc_plugin/lib.rs b/src/librustc_plugin/lib.rs
index 8aa680ca12d10..16ab593e47a72 100644
--- a/src/librustc_plugin/lib.rs
+++ b/src/librustc_plugin/lib.rs
@@ -51,7 +51,6 @@
 //! for more examples.
 
 #![crate_name = "rustc_plugin"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -59,9 +58,11 @@
        html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
-#![feature(staged_api)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 #[macro_use] extern crate syntax;
 
diff --git a/src/librustc_privacy/lib.rs b/src/librustc_privacy/lib.rs
index f63102433c1e6..2ced61f5753a9 100644
--- a/src/librustc_privacy/lib.rs
+++ b/src/librustc_privacy/lib.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![crate_name = "rustc_privacy"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -18,8 +17,10 @@
 #![deny(warnings)]
 
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 extern crate rustc;
 #[macro_use] extern crate syntax;
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index ac556270886ac..ee72aee042e91 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![crate_name = "rustc_resolve"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -19,8 +18,10 @@
 
 #![feature(associated_consts)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 #[macro_use]
 extern crate log;
diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index fd6898d19d84f..cc98754f61042 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![crate_name = "rustc_save_analysis"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -19,8 +18,10 @@
 
 #![feature(custom_attribute)]
 #![allow(unused_attributes)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 #[macro_use] extern crate rustc;
 
diff --git a/src/librustc_trans/lib.rs b/src/librustc_trans/lib.rs
index 111c254772166..ff094d04c8462 100644
--- a/src/librustc_trans/lib.rs
+++ b/src/librustc_trans/lib.rs
@@ -15,7 +15,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "rustc_trans"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -33,12 +32,14 @@
 #![feature(libc)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
 #![feature(slice_patterns)]
-#![feature(staged_api)]
 #![feature(unicode)]
 #![feature(conservative_impl_trait)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 use rustc::dep_graph::WorkProduct;
 use syntax_pos::symbol::Symbol;
 
diff --git a/src/librustc_typeck/lib.rs b/src/librustc_typeck/lib.rs
index 84de4ff2b7b69..99ee1cff7fd22 100644
--- a/src/librustc_typeck/lib.rs
+++ b/src/librustc_typeck/lib.rs
@@ -64,7 +64,6 @@ This API is completely unstable and subject to change.
 */
 
 #![crate_name = "rustc_typeck"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -81,8 +80,10 @@ This API is completely unstable and subject to change.
 #![feature(never_type)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 #[macro_use] extern crate log;
 #[macro_use] extern crate syntax;
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 1156fadf8c02c..d89fa547a89cd 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![crate_name = "rustdoc"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -21,14 +20,16 @@
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(libc)]
-#![feature(rustc_private)]
 #![feature(set_stdio)]
 #![feature(slice_patterns)]
-#![feature(staged_api)]
 #![feature(test)]
 #![feature(unicode)]
 #![feature(vec_remove_item)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 extern crate arena;
 extern crate getopts;
 extern crate env_logger;
diff --git a/src/libserialize/lib.rs b/src/libserialize/lib.rs
index 2b31e2f410806..4eb2cad5c91b9 100644
--- a/src/libserialize/lib.rs
+++ b/src/libserialize/lib.rs
@@ -15,9 +15,9 @@ Core encoding and decoding interfaces.
 */
 
 #![crate_name = "serialize"]
-#![unstable(feature = "rustc_private",
+#![cfg_attr(stage0, unstable(feature = "rustc_private",
             reason = "deprecated in favor of rustc-serialize on crates.io",
-            issue = "27812")]
+            issue = "27812"))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -32,7 +32,7 @@ Core encoding and decoding interfaces.
 #![feature(core_intrinsics)]
 #![feature(i128_type)]
 #![feature(specialization)]
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![cfg_attr(test, feature(test))]
 
 extern crate collections;
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 89c67b88cbde6..32dafcdb582f0 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -15,7 +15,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "syntax"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -24,12 +23,14 @@
        test(attr(deny(warnings))))]
 #![deny(warnings)]
 
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![feature(unicode)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(i128_type)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 extern crate serialize;
 #[macro_use] extern crate log;
 #[macro_use] extern crate bitflags;
diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index e35e79df58520..60f5d24ac9755 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -11,7 +11,6 @@
 //! Syntax extensions in the Rust compiler.
 
 #![crate_name = "syntax_ext"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -20,8 +19,10 @@
 #![deny(warnings)]
 
 #![feature(proc_macro_internals)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
+
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
 
 extern crate fmt_macros;
 extern crate log;
diff --git a/src/libsyntax_pos/lib.rs b/src/libsyntax_pos/lib.rs
index eb86a8e13797b..25f74aeecf404 100644
--- a/src/libsyntax_pos/lib.rs
+++ b/src/libsyntax_pos/lib.rs
@@ -15,7 +15,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "syntax_pos"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -27,10 +26,12 @@
 #![feature(custom_attribute)]
 #![feature(optin_builtin_traits)]
 #![allow(unused_attributes)]
-#![feature(rustc_private)]
-#![feature(staged_api)]
 #![feature(specialization)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 use std::cell::{Cell, RefCell};
 use std::ops::{Add, Sub};
 use std::rc::Rc;
diff --git a/src/libterm/lib.rs b/src/libterm/lib.rs
index 370757c060910..eb0ee6ba154a1 100644
--- a/src/libterm/lib.rs
+++ b/src/libterm/lib.rs
@@ -41,9 +41,6 @@
 //! [ti]: https://en.wikipedia.org/wiki/Terminfo
 
 #![crate_name = "term"]
-#![unstable(feature = "rustc_private",
-            reason = "use the crates.io `term` library instead",
-            issue = "27812")]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -54,13 +51,15 @@
 #![deny(missing_docs)]
 #![deny(warnings)]
 
-#![feature(box_syntax)]
 #![feature(staged_api)]
 #![cfg_attr(windows, feature(libc))]
 // Handle rustfmt skips
 #![feature(custom_attribute)]
 #![allow(unused_attributes)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 use std::io::prelude::*;
 
 pub use terminfo::TerminfoTerminal;