diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index db173d0830815..cc44bddc43e97 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -1097,6 +1097,17 @@ impl TokenTree {
             }
             (&TtToken(sp, token::DocComment(name)), _) => {
                 let stripped = strip_doc_comment_decoration(&name.as_str());
+
+                // Count number of consecutive characters in string.
+                fn max_consecutive(s: &str, c: char) -> usize {
+                    let it = s.chars().scan(0, |count, x| {
+                        if x == c { *count += 1 } else { *count = 0 }
+                        Some(*count)
+                    });
+                    it.max().unwrap_or(0)
+                }
+                let delims = max_consecutive(&stripped, '#') + 1;
+
                 TtDelimited(sp, Rc::new(Delimited {
                     delim: token::Bracket,
                     open_span: sp,
@@ -1104,7 +1115,7 @@ impl TokenTree {
                                                        token::Plain)),
                               TtToken(sp, token::Eq),
                               TtToken(sp, token::Literal(
-                                  token::StrRaw(token::intern(&stripped), 0), None))],
+                                  token::StrRaw(token::intern(&stripped), delims), None))],
                     close_span: sp,
                 }))
             }
diff --git a/src/test/run-pass/issue-27489.rs b/src/test/run-pass/issue-27489.rs
new file mode 100644
index 0000000000000..9eafc21b1def1
--- /dev/null
+++ b/src/test/run-pass/issue-27489.rs
@@ -0,0 +1,42 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+macro_rules! stringify_passthrough {
+    ($t:item) => {
+        pub const TEST: &'static str = stringify!($t);
+    }
+}
+
+mod foo {
+    stringify_passthrough! {
+        /// Hello world
+        pub fn bar() { }
+    }
+}
+
+mod bar {
+    stringify_passthrough! {
+        /// Hello # world
+        pub fn bar() { }
+    }
+}
+
+mod baz {
+    stringify_passthrough! {
+        /// ## Hello "### world #
+        pub fn bar() { }
+    }
+}
+
+fn main() {
+    assert_eq!(foo::TEST, "#[doc = r#\" Hello world\"#]\npub fn bar() { }");
+    assert_eq!(bar::TEST, "#[doc = r##\" Hello # world\"##]\npub fn bar() { }");
+    assert_eq!(baz::TEST, "#[doc = r####\" ## Hello \"### world #\"####]\npub fn bar() { }");
+}