diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index 36827b73ba0..928c934a7ec 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -98,6 +98,7 @@ fn usage(session.session sess, str argv0) {
     log "    -glue              generate glue.bc file";
     log "    -shared            compile a shared-library crate";
     log "    -pp                pretty-print the input instead of compiling";
+    log "    -ls                list the symbols defined by a crate file";
     log "    -L <path>          add a directory to the library search path";
     log "    -h                 display this message";
     log "";
@@ -130,6 +131,7 @@ impure fn main(vec[str] args) {
     let bool do_warn = true;
     let bool shared = false;
     let bool pretty = false;
+    let bool ls = false;
     let bool glue = false;
 
     // FIXME: Maybe we should support -O0, -O1, -Os, etc
@@ -152,6 +154,8 @@ impure fn main(vec[str] args) {
                 shared = true;
             } else if (_str.eq(arg, "-pp")) {
                 pretty = true;
+            } else if (_str.eq(arg, "-ls")) {
+                ls = true;
             } else if (_str.eq(arg, "-o")) {
                 if (i+1u < len) {
                     output_file = some(args.(i+1u));
@@ -214,8 +218,9 @@ impure fn main(vec[str] args) {
             auto env = default_environment(sess, args.(0), ifile);
             if (pretty) {
                 pretty_print_input(sess, env, ifile);
-            }
-            else {
+            } else if (ls) {
+                front.creader.list_file_metadata(ifile, std.io.stdout());
+            } else {
                 alt (output_file) {
                     case (none[str]) {
                         let vec[str] parts = _str.split(ifile, '.' as u8);
diff --git a/src/comp/front/creader.rs b/src/comp/front/creader.rs
index b561367c8b3..7fc6e24726c 100644
--- a/src/comp/front/creader.rs
+++ b/src/comp/front/creader.rs
@@ -566,6 +566,72 @@ fn get_tag_variants(session.session sess, ast.def_id def)
     ret infos;
 }
 
+impure fn list_file_metadata(str path, io.writer out) {
+    alt (get_metadata_section(path)) {
+        case (option.some[vec[u8]](?bytes)) {
+            list_crate_metadata(bytes, out);
+        }
+        case (option.none[vec[u8]]) {
+            out.write_str("Could not find metadata in " + path + ".\n");
+        }
+    }
+}
+
+fn read_path(&ebml.doc d) -> tup(str, uint) {
+    auto desc = ebml.doc_data(d);
+    auto pos = ebml.be_uint_from_bytes(desc, 0u, 4u);
+    auto pathbytes = _vec.slice[u8](desc, 4u, _vec.len[u8](desc));
+    auto path = _str.unsafe_from_bytes(pathbytes);
+    ret tup(path, pos);
+}
+
+impure fn list_crate_metadata(vec[u8] bytes, io.writer out) {
+    auto md = ebml.new_doc(bytes);
+    auto paths = ebml.get_doc(md, metadata.tag_paths);
+    auto items = ebml.get_doc(md, metadata.tag_items);
+    auto index = ebml.get_doc(paths, metadata.tag_index);
+    auto bs = ebml.get_doc(index, metadata.tag_index_buckets);
+    for each (ebml.doc bucket in
+              ebml.tagged_docs(bs, metadata.tag_index_buckets_bucket)) {
+        auto et = metadata.tag_index_buckets_bucket_elt;
+        for each (ebml.doc elt in ebml.tagged_docs(bucket, et)) {
+            auto data = read_path(elt);
+            auto def = ebml.doc_at(bytes, data._1);
+            auto did_doc = ebml.get_doc(def, metadata.tag_def_id);
+            auto did = parse_def_id(ebml.doc_data(did_doc));
+            out.write_str(#fmt("%s (%s)\n", data._0,
+                               describe_def(items, did)));
+        }
+    }
+}
+
+fn describe_def(&ebml.doc items, ast.def_id id) -> str {
+    if (id._0 != 0) {ret "external";}
+    alt (maybe_find_item(id._1 as int, items)) {
+        case (option.some[ebml.doc](?item)) {
+            ret item_kind_to_str(item_kind(item));
+        }
+        case (option.none[ebml.doc]) {
+            ret "??"; // Native modules don't seem to get item entries.
+        }
+    }
+}
+
+fn item_kind_to_str(u8 kind) -> str {
+    alt (kind as char) {
+        case ('c') {ret "const";}
+        case ('f') {ret "fn";}
+        case ('F') {ret "native fn";}
+        case ('y') {ret "type";}
+        case ('o') {ret "obj";}
+        case ('T') {ret "native type";}
+        case ('t') {ret "type";}
+        case ('m') {ret "mod";}
+        case ('n') {ret "native mod";}
+        case ('v') {ret "tag";}
+    }
+}
+
 // Local Variables:
 // mode: rust
 // fill-column: 78;