diff --git a/src/librustdoc/html/highlight.rs b/src/librustdoc/html/highlight.rs
index e6b236deac4e..081f950e40db 100644
--- a/src/librustdoc/html/highlight.rs
+++ b/src/librustdoc/html/highlight.rs
@@ -34,12 +34,18 @@ use syntax_pos::Span;
 
 /// Highlights `src`, returning the HTML output.
 pub fn render_with_highlighting(src: &str, class: Option<&str>, id: Option<&str>,
-                                extension: Option<&str>) -> String {
+                                extension: Option<&str>,
+                                tooltip: Option<(&str, &str)>) -> String {
     debug!("highlighting: ================\n{}\n==============", src);
     let sess = parse::ParseSess::new(FilePathMapping::empty());
     let fm = sess.codemap().new_filemap("<stdin>".to_string(), src.to_string());
 
     let mut out = Vec::new();
+    if let Some((tooltip, class)) = tooltip {
+        write!(out, "<div class='information'><div class='tooltip {}'>⚠<span \
+                     class='tooltiptext'>{}</span></div></div>",
+               class, tooltip).unwrap();
+    }
     write_header(class, id, &mut out).unwrap();
 
     let mut classifier = Classifier::new(lexer::StringReader::new(&sess, fm), sess.codemap());
diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index 2d14c02bf8a5..3b03acf99081 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -158,10 +158,15 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'a, I> {
 
     fn next(&mut self) -> Option<Self::Item> {
         let event = self.inner.next();
+        let compile_fail;
+        let ignore;
         if let Some(Event::Start(Tag::CodeBlock(lang))) = event {
-            if !LangString::parse(&lang).rust {
+            let parse_result = LangString::parse(&lang);
+            if !parse_result.rust {
                 return Some(Event::Start(Tag::CodeBlock(lang)));
             }
+            compile_fail = parse_result.compile_fail;
+            ignore = parse_result.ignore;
         } else {
             return event;
         }
@@ -220,11 +225,22 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'a, I> {
                     url, test_escaped, channel
                 ))
             });
+            let tooltip = if ignore {
+                Some(("Be careful when using this code, it's not being tested!", "ignore"))
+            } else if compile_fail {
+                Some(("This code doesn't compile so be extra careful!", "compile_fail"))
+            } else {
+                None
+            };
             s.push_str(&highlight::render_with_highlighting(
                         &text,
-                        Some("rust-example-rendered"),
+                        Some(&format!("rust-example-rendered{}",
+                                      if ignore { " ignore" }
+                                      else if compile_fail { " compile_fail" }
+                                      else { "" })),
                         None,
-                        playground_button.as_ref().map(String::as_str)));
+                        playground_button.as_ref().map(String::as_str),
+                        tooltip));
             Some(Event::Html(s.into()))
         })
     }
@@ -554,12 +570,18 @@ pub fn render(w: &mut fmt::Formatter,
             let origtext = str::from_utf8(text).unwrap();
             let origtext = origtext.trim_left();
             debug!("docblock: ==============\n{:?}\n=======", text);
+            let mut compile_fail = false;
+            let mut ignore = false;
+
             let rendered = if lang.is_null() || origtext.is_empty() {
                 false
             } else {
                 let rlang = (*lang).as_bytes();
                 let rlang = str::from_utf8(rlang).unwrap();
-                if !LangString::parse(rlang).rust {
+                let parse_result = LangString::parse(rlang);
+                compile_fail = parse_result.compile_fail;
+                ignore = parse_result.ignore;
+                if !parse_result.rust {
                     (my_opaque.dfltblk)(ob, orig_text, lang,
                                         opaque as *const hoedown_renderer_data,
                                         line);
@@ -614,11 +636,22 @@ pub fn render(w: &mut fmt::Formatter,
                         url, test_escaped, channel
                     ))
                 });
+                let tooltip = if ignore {
+                    Some(("Be careful when using this code, it's not being tested!", "ignore"))
+                } else if compile_fail {
+                    Some(("This code doesn't compile so be extra careful!", "compile_fail"))
+                } else {
+                    None
+                };
                 s.push_str(&highlight::render_with_highlighting(
                                &text,
-                               Some("rust-example-rendered"),
+                               Some(&format!("rust-example-rendered{}",
+                                             if ignore { " ignore" }
+                                             else if compile_fail { " compile_fail" }
+                                             else { "" })),
                                None,
-                               playground_button.as_ref().map(String::as_str)));
+                               playground_button.as_ref().map(String::as_str),
+                               tooltip));
                 hoedown_buffer_put(ob, s.as_ptr(), s.len());
             })
         }
diff --git a/src/librustdoc/html/render.rs b/src/librustdoc/html/render.rs
index 46bb119cf9c9..993462a8d444 100644
--- a/src/librustdoc/html/render.rs
+++ b/src/librustdoc/html/render.rs
@@ -1839,6 +1839,7 @@ fn render_assoc_const_value(item: &clean::Item) -> String {
                 None,
                 None,
                 None,
+                None,
             )
         }
         _ => String::new(),
@@ -3678,7 +3679,8 @@ impl<'a> fmt::Display for Source<'a> {
             write!(fmt, "<span id=\"{0}\">{0:1$}</span>\n", i, cols)?;
         }
         write!(fmt, "</pre>")?;
-        write!(fmt, "{}", highlight::render_with_highlighting(s, None, None, None))?;
+        write!(fmt, "{}",
+               highlight::render_with_highlighting(s, None, None, None, None))?;
         Ok(())
     }
 }
@@ -3688,6 +3690,7 @@ fn item_macro(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
     w.write_str(&highlight::render_with_highlighting(&t.source,
                                                      Some("macro"),
                                                      None,
+                                                     None,
                                                      None))?;
     document(w, cx, it)
 }
diff --git a/src/librustdoc/html/static/main.js b/src/librustdoc/html/static/main.js
index 8ec9cd8660a8..da4430d8a153 100644
--- a/src/librustdoc/html/static/main.js
+++ b/src/librustdoc/html/static/main.js
@@ -1296,6 +1296,24 @@
             collapseDocs(i_e.previousSibling.childNodes[0]);
         });
     });
+
+    onEach(document.getElementsByClassName('rust-example-rendered'), function(e) {
+        if (hasClass(e, 'compile_fail')) {
+            e.addEventListener("mouseover", function(event) {
+                e.previousElementSibling.childNodes[0].style.color = '#f00';
+            });
+            e.addEventListener("mouseout", function(event) {
+                e.previousElementSibling.childNodes[0].style.color = '';
+            });
+        } else if (hasClass(e, 'ignore')) {
+            e.addEventListener("mouseover", function(event) {
+                e.previousElementSibling.childNodes[0].style.color = '#ff9200';
+            });
+            e.addEventListener("mouseout", function(event) {
+                e.previousElementSibling.childNodes[0].style.color = '';
+            });
+        }
+    });
 }());
 
 // Sets the focus on the search bar at the top of the page
diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index ca55d0e5d2a8..c15051376bf2 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -612,7 +612,6 @@ pre.rust .question-mark {
 	font-weight: bold;
 }
 
-pre.rust { position: relative; }
 a.test-arrow {
 	display: inline-block;
 	position: absolute;
@@ -813,3 +812,44 @@ span.since {
 		display: none;
 	}
 }
+
+.information {
+	position: absolute;
+	left: -1px;
+	margin-top: 7px;
+}
+
+.tooltip {
+	position: relative;
+	display: inline-block;
+	cursor: pointer;
+}
+
+.tooltip .tooltiptext {
+	width: 120px;
+	display: none;
+	background-color: black;
+	color: #fff;
+	text-align: center;
+	padding: 5px 3px;
+	border-radius: 6px;
+	margin-left: 5px;
+	top: -5px;
+	left: 105%;
+	z-index: 1;
+}
+
+.tooltip:hover .tooltiptext {
+	display: inline;
+}
+
+.tooltip .tooltiptext::after {
+	content: " ";
+	position: absolute;
+	top: 50%;
+	left: 11px;
+	margin-top: -5px;
+	border-width: 5px;
+	border-style: solid;
+	border-color: transparent black transparent transparent;
+}
diff --git a/src/librustdoc/html/static/styles/main.css b/src/librustdoc/html/static/styles/main.css
index c5f4272b932f..42d0ec704f45 100644
--- a/src/librustdoc/html/static/styles/main.css
+++ b/src/librustdoc/html/static/styles/main.css
@@ -202,4 +202,36 @@ a.test-arrow:hover{
 
 :target > code {
 	background: #FDFFD3;
-}
\ No newline at end of file
+}
+
+pre.compile_fail {
+	border-left: 2px solid rgba(255,0,0,.4);
+}
+
+pre.compile_fail:hover, .information:hover + pre.compile_fail {
+	border-left: 2px solid #f00;
+}
+
+pre.ignore {
+	border-left: 2px solid rgba(255,142,0,.4);
+}
+
+pre.ignore:hover, .information:hover + pre.ignore {
+	border-left: 2px solid #ff9200;
+}
+
+.tooltip.compile_fail {
+	color: rgba(255,0,0,.3);
+}
+
+.information > .compile_fail:hover {
+	color: #f00;
+}
+
+.tooltip.ignore {
+	color: rgba(255,142,0,.3);
+}
+
+.information > .ignore:hover {
+	color: rgba(255,142,0,1);
+}
diff --git a/src/test/rustdoc/codeblock-title.rs b/src/test/rustdoc/codeblock-title.rs
new file mode 100644
index 000000000000..accefd6b65f2
--- /dev/null
+++ b/src/test/rustdoc/codeblock-title.rs
@@ -0,0 +1,31 @@
+// 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.
+
+#![crate_name = "foo"]
+
+// ignore-tidy-linelength
+
+// @has foo/fn.bar.html '//*[@class="tooltip compile_fail"]/span' "This code doesn't compile so be extra careful!"
+// @has foo/fn.bar.html '//*[@class="tooltip ignore"]/span' "Be careful when using this code, it's not being tested!"
+
+/// foo
+///
+/// ```compile_fail
+/// foo();
+/// ```
+///
+/// ```ignore (tidy)
+/// goo();
+/// ```
+///
+/// ```
+/// let x = 0;
+/// ```
+pub fn bar() -> usize { 2 }