diff --git a/src/librustc_metadata/creader.rs b/src/librustc_metadata/creader.rs
index cdeee92cb07..1e227b8a1a6 100644
--- a/src/librustc_metadata/creader.rs
+++ b/src/librustc_metadata/creader.rs
@@ -536,7 +536,7 @@ impl<'a> CrateLoader<'a> {
                 Ok(f) => f,
                 Err(err) => self.sess.span_fatal(span, &err),
             };
-            mem::transmute::<*mut u8, fn(&mut Registry)>(sym)
+            mem::transmute::<*mut u8, fn(&mut dyn Registry)>(sym)
         };
 
         struct MyRegistrar {
@@ -1019,7 +1019,7 @@ impl<'a> CrateLoader<'a> {
     fn inject_dependency_if(&self,
                             krate: CrateNum,
                             what: &str,
-                            needs_dep: &Fn(&cstore::CrateMetadata) -> bool) {
+                            needs_dep: &dyn Fn(&cstore::CrateMetadata) -> bool) {
         // don't perform this validation if the session has errors, as one of
         // those errors may indicate a circular dependency which could cause
         // this to stack overflow.
diff --git a/src/librustc_metadata/cstore.rs b/src/librustc_metadata/cstore.rs
index 2bc5f607486..d93a7f9526e 100644
--- a/src/librustc_metadata/cstore.rs
+++ b/src/librustc_metadata/cstore.rs
@@ -90,11 +90,11 @@ pub struct CStore {
     metas: RwLock<IndexVec<CrateNum, Option<Lrc<CrateMetadata>>>>,
     /// Map from NodeId's of local extern crate statements to crate numbers
     extern_mod_crate_map: Lock<NodeMap<CrateNum>>,
-    pub metadata_loader: Box<MetadataLoader + Sync>,
+    pub metadata_loader: Box<dyn MetadataLoader + Sync>,
 }
 
 impl CStore {
-    pub fn new(metadata_loader: Box<MetadataLoader + Sync>) -> CStore {
+    pub fn new(metadata_loader: Box<dyn MetadataLoader + Sync>) -> CStore {
         CStore {
             // We add an empty entry for LOCAL_CRATE (which maps to zero) in
             // order to make array indices in `metas` match with the
diff --git a/src/librustc_metadata/cstore_impl.rs b/src/librustc_metadata/cstore_impl.rs
index cded812b5f0..d5078642147 100644
--- a/src/librustc_metadata/cstore_impl.rs
+++ b/src/librustc_metadata/cstore_impl.rs
@@ -413,11 +413,11 @@ pub fn provide<'tcx>(providers: &mut Providers<'tcx>) {
 }
 
 impl CrateStore for cstore::CStore {
-    fn crate_data_as_rc_any(&self, krate: CrateNum) -> Lrc<Any> {
+    fn crate_data_as_rc_any(&self, krate: CrateNum) -> Lrc<dyn Any> {
         self.get_crate_data(krate)
     }
 
-    fn metadata_loader(&self) -> &MetadataLoader {
+    fn metadata_loader(&self) -> &dyn MetadataLoader {
         &*self.metadata_loader
     }
 
diff --git a/src/librustc_metadata/decoder.rs b/src/librustc_metadata/decoder.rs
index 38149d1ca50..b8c64383950 100644
--- a/src/librustc_metadata/decoder.rs
+++ b/src/librustc_metadata/decoder.rs
@@ -391,7 +391,7 @@ impl<'a, 'tcx> MetadataBlob {
     }
 
     pub fn list_crate_metadata(&self,
-                               out: &mut io::Write) -> io::Result<()> {
+                               out: &mut dyn io::Write) -> io::Result<()> {
         write!(out, "=External Dependencies=\n")?;
         let root = self.get_root();
         for (i, dep) in root.crate_deps
diff --git a/src/librustc_metadata/lib.rs b/src/librustc_metadata/lib.rs
index dad1030cb61..5c9915e94e5 100644
--- a/src/librustc_metadata/lib.rs
+++ b/src/librustc_metadata/lib.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![deny(bare_trait_objects)]
+
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
        html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
        html_root_url = "https://doc.rust-lang.org/nightly/")]
diff --git a/src/librustc_metadata/locator.rs b/src/librustc_metadata/locator.rs
index 9b1b48efca5..b747624338c 100644
--- a/src/librustc_metadata/locator.rs
+++ b/src/librustc_metadata/locator.rs
@@ -273,7 +273,7 @@ pub struct Context<'a> {
     pub rejected_via_filename: Vec<CrateMismatch>,
     pub should_match_name: bool,
     pub is_proc_macro: Option<bool>,
-    pub metadata_loader: &'a MetadataLoader,
+    pub metadata_loader: &'a dyn MetadataLoader,
 }
 
 pub struct CratePaths {
@@ -842,7 +842,7 @@ impl<'a> Context<'a> {
 fn get_metadata_section(target: &Target,
                         flavor: CrateFlavor,
                         filename: &Path,
-                        loader: &MetadataLoader)
+                        loader: &dyn MetadataLoader)
                         -> Result<MetadataBlob, String> {
     let start = Instant::now();
     let ret = get_metadata_section_imp(target, flavor, filename, loader);
@@ -855,7 +855,7 @@ fn get_metadata_section(target: &Target,
 fn get_metadata_section_imp(target: &Target,
                             flavor: CrateFlavor,
                             filename: &Path,
-                            loader: &MetadataLoader)
+                            loader: &dyn MetadataLoader)
                             -> Result<MetadataBlob, String> {
     if !filename.exists() {
         return Err(format!("no such file: '{}'", filename.display()));
@@ -904,8 +904,8 @@ fn get_metadata_section_imp(target: &Target,
 // A diagnostic function for dumping crate metadata to an output stream
 pub fn list_file_metadata(target: &Target,
                           path: &Path,
-                          loader: &MetadataLoader,
-                          out: &mut io::Write)
+                          loader: &dyn MetadataLoader,
+                          out: &mut dyn io::Write)
                           -> io::Result<()> {
     let filename = path.file_name().unwrap().to_str().unwrap();
     let flavor = if filename.ends_with(".rlib") {