diff --git a/src/librustdoc/html/highlight.rs b/src/librustdoc/html/highlight.rs
index e6b236deac4e..cc1da35a9975 100644
--- a/src/librustdoc/html/highlight.rs
+++ b/src/librustdoc/html/highlight.rs
@@ -22,6 +22,7 @@
 
 use html::escape::Escape;
 
+use std::collections::HashMap;
 use std::fmt::Display;
 use std::io;
 use std::io::prelude::*;
@@ -34,12 +35,18 @@ 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>,
+                                extras: Option<HashMap<String, String>>) -> 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());
@@ -389,12 +396,18 @@ impl Class {
 
 fn write_header(class: Option<&str>,
                 id: Option<&str>,
-                out: &mut Write)
+                out: &mut Write,
+                extras: Option<HashMap<String, String>>)
                 -> io::Result<()> {
     write!(out, "<pre ")?;
     if let Some(id) = id {
         write!(out, "id='{}' ", id)?;
     }
+    if let Some(extras) = extras {
+        for (key, value) in &extras {
+            write!(out, "{}=\"{}\" ", key, value)?;
+        }
+    }
     write!(out, "class=\"rust {}\">\n", class.unwrap_or(""))
 }
 
diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index 2d14c02bf8a5..d9fb35c4c269 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 +225,28 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'a, I> {
                     url, test_escaped, channel
                 ))
             });
+            let title = if ignore {
+                let mut tmp = HashMap::new();
+                tmp.insert("title".to_owned(),
+                           "Be careful when using this code, it's not being tested!".to_owned());
+                Some(tmp)
+            } else if compile_fail {
+                let mut tmp = HashMap::new();
+                tmp.insert("title".to_owned(),
+                           "This code doesn't compile so be extra careful!".to_owned());
+                Some(tmp)
+            } 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),
+                        title));
             Some(Event::Html(s.into()))
         })
     }
@@ -554,12 +576,18 @@ 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 +642,30 @@ pub fn render(w: &mut fmt::Formatter,
                         url, test_escaped, channel
                     ))
                 });
+                let title = if ignore {
+                    let mut tmp = HashMap::new();
+                    tmp.insert("title".to_owned(),
+                               "Be careful when using this code, it's not being \
+                                tested!".to_owned());
+                    Some(tmp)
+                } else if compile_fail {
+                    let mut tmp = HashMap::new();
+                    tmp.insert("title".to_owned(),
+                               "This code doesn't compile so be extra \
+                                careful!".to_owned());
+                    Some(tmp)
+                } 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),
+                               title));
                 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..f911ddb4d4f5 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 +3679,7 @@ 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 +3689,7 @@ 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/styles/main.css b/src/librustdoc/html/static/styles/main.css
index c5f4272b932f..18b40b3d60c1 100644
--- a/src/librustdoc/html/static/styles/main.css
+++ b/src/librustdoc/html/static/styles/main.css
@@ -202,4 +202,12 @@ a.test-arrow:hover{
 
 :target > code {
 	background: #FDFFD3;
+}
+
+pre.compile_fail {
+	box-shadow: -6px 0 5px -3px #f00;
+}
+
+pre.ignore {
+	box-shadow: -6px 0 5px -3px #ff9200;
 }
\ No newline at end of file