diff --git a/src/librustdoc/html/highlight.rs b/src/librustdoc/html/highlight.rs
index ece3ee640e2a6..15a4f4b10ad6f 100644
--- a/src/librustdoc/html/highlight.rs
+++ b/src/librustdoc/html/highlight.rs
@@ -9,8 +9,9 @@ use crate::clean::PrimitiveType;
 use crate::html::escape::Escape;
 use crate::html::render::Context;
 
-use std::fmt::{Display, Write};
-use std::iter::Peekable;
+use std::borrow::Cow;
+use std::fmt::{Debug, Display, Write};
+use std::iter::{once, Peekable};
 
 use rustc_lexer::{LiteralKind, TokenKind};
 use rustc_span::edition::Edition;
@@ -18,6 +19,7 @@ use rustc_span::symbol::Symbol;
 use rustc_span::{BytePos, Span, DUMMY_SP};
 
 use super::format::{self, Buffer};
+use super::markdown::Line;
 use super::render::LinkFromSrc;
 
 /// This type is needed in case we want to render links on items to allow to go to their definition.
@@ -31,7 +33,7 @@ crate struct ContextInfo<'a, 'b, 'c> {
 }
 
 /// Highlights `src`, returning the HTML output.
-crate fn render_with_highlighting(
+crate fn render_source_with_highlighting(
     src: &str,
     out: &mut Buffer,
     class: Option<&str>,
@@ -41,7 +43,31 @@ crate fn render_with_highlighting(
     extra_content: Option<Buffer>,
     context_info: Option<ContextInfo<'_, '_, '_>>,
 ) {
-    debug!("highlighting: ================\n{}\n==============", src);
+    render_with_highlighting(
+        once(Line::Shown(Cow::Borrowed(src))),
+        out,
+        class,
+        playground_button,
+        tooltip,
+        edition,
+        extra_content,
+        context_info,
+    )
+}
+
+/// Highlights `src` containing potential hidden lines, returning the HTML output. If you don't have
+/// hidden lines, use [`render_source_with_highlighting`] instead.
+crate fn render_with_highlighting<'a>(
+    src: impl Iterator<Item = Line<'a>> + Debug,
+    out: &mut Buffer,
+    class: Option<&str>,
+    playground_button: Option<&str>,
+    tooltip: Option<(Option<Edition>, &str)>,
+    edition: Edition,
+    extra_content: Option<Buffer>,
+    context_info: Option<ContextInfo<'_, '_, '_>>,
+) {
+    debug!("highlighting: ================\n{:?}\n==============", src);
     if let Some((edition_info, class)) = tooltip {
         write!(
             out,
@@ -56,8 +82,8 @@ crate fn render_with_highlighting(
     }
 
     write_header(out, class, extra_content);
-    write_code(out, &src, edition, context_info);
-    write_footer(out, playground_button);
+    let expand = write_code(out, src, edition, context_info);
+    write_footer(out, playground_button, expand);
 }
 
 fn write_header(out: &mut Buffer, class: Option<&str>, extra_content: Option<Buffer>) {
@@ -86,13 +112,31 @@ fn write_header(out: &mut Buffer, class: Option<&str>, extra_content: Option<Buf
 /// More explanations about spans and how we use them here are provided in the
 fn write_code(
     out: &mut Buffer,
-    src: &str,
+    src: impl Iterator<Item = Line<'a>>,
     edition: Edition,
     context_info: Option<ContextInfo<'_, '_, '_>>,
-) {
-    // This replace allows to fix how the code source with DOS backline characters is displayed.
-    let src = src.replace("\r\n", "\n");
-    Classifier::new(&src, edition, context_info.as_ref().map(|c| c.file_span).unwrap_or(DUMMY_SP))
+) -> bool {
+    let mut iter = src.peekable();
+    let mut expand = false;
+
+    // For each `Line`, we replace DOS backlines with '\n'. This replace allows to fix how the code
+    // source with DOS backline characters is displayed.
+    while let Some(line) = iter.next() {
+        let (before, text, after) = match line {
+            Line::Hidden(text) => {
+                expand = true;
+                ("<span class=\"hidden\">", text.replace("\r\n", "\n"), "</span>")
+            }
+            Line::Shown(text) => ("", text.replace("\r\n", "\n"), ""),
+        };
+        if !before.is_empty() {
+            out.push_str(before);
+        }
+        Classifier::new(
+            &text.replace("\r\n", "\n"),
+            edition,
+            context_info.as_ref().map(|c| c.file_span).unwrap_or(DUMMY_SP),
+        )
         .highlight(&mut |highlight| {
             match highlight {
                 Highlight::Token { text, class } => string(out, Escape(text), class, &context_info),
@@ -100,10 +144,27 @@ fn write_code(
                 Highlight::ExitSpan => exit_span(out),
             };
         });
+        if iter.peek().is_some() && !text.ends_with('\n') {
+            out.push_str("\n");
+        }
+        if !after.is_empty() {
+            out.push_str(after);
+        }
+    }
+    expand
 }
 
-fn write_footer(out: &mut Buffer, playground_button: Option<&str>) {
-    writeln!(out, "</code></pre>{}</div>", playground_button.unwrap_or_default());
+fn write_footer(out: &mut Buffer, playground_button: Option<&str>, expand: bool) {
+    writeln!(
+        out,
+        "</code></pre>\
+         <div class=\"code-buttons\">\
+             {}{}<button class=\"copy-code\" onclick=\"copyCode(this)\"></button>\
+         </div>\
+        </div>",
+        playground_button.unwrap_or_default(),
+        if expand { "<button class=\"expand\" onclick=\"expandCode(this)\"></button>" } else { "" },
+    );
 }
 
 /// How a span of text is classified. Mostly corresponds to token kinds.
diff --git a/src/librustdoc/html/highlight/tests.rs b/src/librustdoc/html/highlight/tests.rs
index 68592ae96c187..7e09a60083e7b 100644
--- a/src/librustdoc/html/highlight/tests.rs
+++ b/src/librustdoc/html/highlight/tests.rs
@@ -1,9 +1,13 @@
 use super::write_code;
 use crate::html::format::Buffer;
+use crate::html::markdown::Line;
 use expect_test::expect_file;
 use rustc_span::create_default_session_globals_then;
 use rustc_span::edition::Edition;
 
+use std::borrow::Cow;
+use std::iter::once;
+
 const STYLE: &str = r#"
 <style>
 .kw { color: #8959A8; }
@@ -20,6 +24,7 @@ const STYLE: &str = r#"
 fn test_html_highlighting() {
     create_default_session_globals_then(|| {
         let src = include_str!("fixtures/sample.rs");
+        let src = once(Line::Shown(Cow::Borrowed(src)));
         let html = {
             let mut out = Buffer::new();
             write_code(&mut out, src, Edition::Edition2018, None);
@@ -35,6 +40,7 @@ fn test_dos_backline() {
         let src = "pub fn foo() {\r\n\
     println!(\"foo\");\r\n\
 }\r\n";
+        let src = once(Line::Shown(Cow::Borrowed(src)));
         let mut html = Buffer::new();
         write_code(&mut html, src, Edition::Edition2018, None);
         expect_file!["fixtures/dos_line.html"].assert_eq(&html.into_inner());
@@ -49,6 +55,7 @@ use self::whatever;
 let x = super::b::foo;
 let y = Self::whatever;";
 
+        let src = once(Line::Shown(Cow::Borrowed(src)));
         let mut html = Buffer::new();
         write_code(&mut html, src, Edition::Edition2018, None);
         expect_file!["fixtures/highlight.html"].assert_eq(&html.into_inner());
diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index c971e231463cd..fe068d39b3c2c 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -123,20 +123,14 @@ impl ErrorCodes {
 /// Controls whether a line will be hidden or shown in HTML output.
 ///
 /// All lines are used in documentation tests.
-enum Line<'a> {
+#[derive(Debug)]
+crate enum Line<'a> {
     Hidden(&'a str),
     Shown(Cow<'a, str>),
 }
 
 impl<'a> Line<'a> {
-    fn for_html(self) -> Option<Cow<'a, str>> {
-        match self {
-            Line::Shown(l) => Some(l),
-            Line::Hidden(_) => None,
-        }
-    }
-
-    fn for_code(self) -> Cow<'a, str> {
+    crate fn for_code(self) -> Cow<'a, str> {
         match self {
             Line::Shown(l) => l,
             Line::Hidden(l) => Cow::Borrowed(l),
@@ -229,8 +223,7 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'_, 'a, I> {
                 _ => {}
             }
         }
-        let lines = origtext.lines().filter_map(|l| map_line(l).for_html());
-        let text = lines.collect::<Vec<Cow<'_, str>>>().join("\n");
+        let lines = origtext.lines().map(map_line);
 
         let parse_result = match kind {
             CodeBlockKind::Fenced(ref lang) => {
@@ -243,7 +236,7 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'_, 'a, I> {
                                  <pre class=\"language-{}\"><code>{}</code></pre>\
                              </div>",
                             lang,
-                            Escape(&text),
+                            Escape(&origtext),
                         )
                         .into(),
                     ));
@@ -326,7 +319,7 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'_, 'a, I> {
         let mut s = Buffer::new();
         s.push_str("\n");
         highlight::render_with_highlighting(
-            &text,
+            lines,
             &mut s,
             Some(&format!(
                 "rust-example-rendered{}",
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index 52505f2d63471..bb0f45c24a555 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -1115,7 +1115,7 @@ fn item_enum(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, e: &clean::Enum
 
 fn item_macro(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, t: &clean::Macro) {
     wrap_into_docblock(w, |w| {
-        highlight::render_with_highlighting(
+        highlight::render_source_with_highlighting(
             &t.source,
             w,
             Some("macro"),
diff --git a/src/librustdoc/html/render/write_shared.rs b/src/librustdoc/html/render/write_shared.rs
index 1dd0917699bf4..5553d09733592 100644
--- a/src/librustdoc/html/render/write_shared.rs
+++ b/src/librustdoc/html/render/write_shared.rs
@@ -179,6 +179,7 @@ pub(super) fn write_shared(
         cx.write_shared(SharedResource::InvocationSpecific { basename: p }, content, &options.emit)
     };
 
+    // This is required because the name of the image changes based on the current toolchain.
     fn add_background_image_to_css(
         cx: &Context<'_>,
         css: &mut String,
@@ -218,6 +219,12 @@ pub(super) fn write_shared(
 
     // Add all the static files. These may already exist, but we just
     // overwrite them anyway to make sure that they're fresh and up-to-date.
+    let mut rustdoc_css = static_files::RUSTDOC_CSS.to_owned();
+    add_background_image_to_css(cx, &mut rustdoc_css, ".copy-code", "clipboard.svg");
+    add_background_image_to_css(cx, &mut rustdoc_css, ".expand", "eye.svg");
+    add_background_image_to_css(cx, &mut rustdoc_css, ".collapse", "eye-slash.svg");
+    write_minify("rustdoc.css", rustdoc_css, cx, options)?;
+
     write_minify("settings.css", static_files::SETTINGS_CSS, cx, options)?;
     write_minify("noscript.css", static_files::NOSCRIPT_CSS, cx, options)?;
 
@@ -259,6 +266,8 @@ pub(super) fn write_shared(
     write_toolchain("down-arrow.svg", static_files::DOWN_ARROW_SVG)?;
     write_toolchain("toggle-minus.svg", static_files::TOGGLE_MINUS_PNG)?;
     write_toolchain("toggle-plus.svg", static_files::TOGGLE_PLUS_PNG)?;
+    write_toolchain("eye.svg", static_files::EXPAND_SVG)?;
+    write_toolchain("eye-slash.svg", static_files::COLLAPSE_SVG)?;
 
     let mut themes: Vec<&String> = themes.iter().collect();
     themes.sort();
diff --git a/src/librustdoc/html/sources.rs b/src/librustdoc/html/sources.rs
index 71c64231a210e..1d7314a47aa20 100644
--- a/src/librustdoc/html/sources.rs
+++ b/src/librustdoc/html/sources.rs
@@ -264,7 +264,7 @@ fn print_src(
         writeln!(line_numbers, "<span id=\"{0}\">{0:1$}</span>", i, cols);
     }
     line_numbers.write_str("</pre>");
-    highlight::render_with_highlighting(
+    highlight::render_source_with_highlighting(
         s,
         buf,
         None,
diff --git a/src/librustdoc/html/static/css/noscript.css b/src/librustdoc/html/static/css/noscript.css
index 0a196edd53b1d..095559e16f270 100644
--- a/src/librustdoc/html/static/css/noscript.css
+++ b/src/librustdoc/html/static/css/noscript.css
@@ -9,7 +9,7 @@ rules.
 	margin-left: 0 !important;
 }
 
-#copy-path {
+#copy-path, .copy-code, .expand, .collapse {
 	/* It requires JS to work so no need to display it in this case. */
 	display: none;
 }
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 2d4bfc62af68e..5405457478863 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -190,7 +190,8 @@ details.undocumented > summary::before,
 div.impl-items > div:not(.docblock):not(.item-info),
 .content ul.crate a.crate, a.srclink,
 /* This selector is for the items listed in the "all items" page. */
-#main > ul.docblock > li > a {
+#main > ul.docblock > li > a,
+.copy-code {
 	font-family: "Fira Sans", Arial, sans-serif;
 }
 
@@ -240,7 +241,7 @@ details:not(.rustdoc-toggle) summary {
 	margin-bottom: .6em;
 }
 
-code, pre, a.test-arrow, .code-header {
+code, pre, div.code-buttons, .code-header {
 	font-family: "Source Code Pro", monospace;
 }
 .docblock code, .docblock-short code {
@@ -1039,19 +1040,33 @@ pre.rust .question-mark {
 	font-weight: bold;
 }
 
-a.test-arrow {
-	display: inline-block;
+.code-buttons {
+	display: flex;
 	position: absolute;
-	padding: 5px 10px 5px 10px;
-	border-radius: 5px;
-	font-size: 130%;
 	top: 5px;
 	right: 5px;
 	z-index: 1;
+	font-size: 130%;
+}
+a.test-arrow {
+	border-radius: 5px;
+	padding: 5px 10px 5px 10px;
+	display: inline-block;
 }
 a.test-arrow:hover{
 	text-decoration: none;
 }
+.copy-code, .expand, .collapse {
+	width: 21px;
+	background-size: contain;
+	background-color: transparent;
+	background-repeat: no-repeat;
+	border: 0;
+	background-position: center;
+	border-radius: 4px;
+	cursor: pointer;
+	margin-left: 7px;
+}
 
 .section-header:hover a:before {
 	position: absolute;
@@ -1242,6 +1257,11 @@ pre.rust {
 	-moz-tab-size: 4;
 }
 
+pre .data-hidden {
+	width: 100%;
+	display: block;
+}
+
 .search-failed {
 	text-align: center;
 	margin-top: 20px;
diff --git a/src/librustdoc/html/static/css/themes/ayu.css b/src/librustdoc/html/static/css/themes/ayu.css
index eada8f4a04dae..9d6894b6adfc0 100644
--- a/src/librustdoc/html/static/css/themes/ayu.css
+++ b/src/librustdoc/html/static/css/themes/ayu.css
@@ -57,6 +57,10 @@ pre, .rustdoc.source .example-wrap {
 	background-color: #191f26;
 }
 
+pre .data-hidden {
+	background-color: #313942;
+}
+
 .sidebar {
 	background-color: #14191f;
 }
@@ -331,12 +335,19 @@ a.test-arrow {
 	border-radius: 4px;
 	background-color: rgba(57, 175, 215, 0.09);
 }
-
 a.test-arrow:hover {
 	background-color: rgba(57, 175, 215, 0.368);
 	color: #c5c5c5;
 }
 
+.copy-code, .expand, .collapse {
+	filter: invert(70%);
+	color: #fff;
+}
+.copy-code:hover, .expand:hover, .collapse:hover {
+	filter: invert(100%);
+}
+
 .toggle-label,
 .code-attribute {
 	color: #999;
diff --git a/src/librustdoc/html/static/css/themes/dark.css b/src/librustdoc/html/static/css/themes/dark.css
index d9348be6994e2..86dcd7bc7cff8 100644
--- a/src/librustdoc/html/static/css/themes/dark.css
+++ b/src/librustdoc/html/static/css/themes/dark.css
@@ -28,6 +28,10 @@ pre, .rustdoc.source .example-wrap {
 	background-color: #2A2A2A;
 }
 
+pre .data-hidden {
+	background-color: #373636;
+}
+
 .sidebar {
 	background-color: #505050;
 }
@@ -190,6 +194,13 @@ body.source .example-wrap pre.rust a {
 a.test-arrow {
 	color: #dedede;
 }
+.copy-code, .expand, .collapse {
+	filter: invert(50%);
+	color: #999;
+}
+.copy-code:hover, .expand:hover, .collapse:hover {
+	filter: invert(65%);
+}
 
 details.rustdoc-toggle > summary.hideme > span,
 details.rustdoc-toggle > summary::before,
diff --git a/src/librustdoc/html/static/css/themes/light.css b/src/librustdoc/html/static/css/themes/light.css
index 0ffe5929ea593..de3beb34a347d 100644
--- a/src/librustdoc/html/static/css/themes/light.css
+++ b/src/librustdoc/html/static/css/themes/light.css
@@ -30,6 +30,10 @@ pre, .rustdoc.source .example-wrap {
 	background-color: #F5F5F5;
 }
 
+pre .data-hidden {
+	background-color: #E6E4E4;
+}
+
 .sidebar {
 	background-color: #F1F1F1;
 }
@@ -185,6 +189,13 @@ body.source .example-wrap pre.rust a {
 a.test-arrow {
 	color: #f5f5f5;
 }
+.copy-code, .expand, .collapse {
+	filter: invert(50%);
+	color: #999;
+}
+.copy-code:hover, .expand:hover, .collapse:hover {
+	filter: invert(35%);
+}
 
 details.rustdoc-toggle > summary.hideme > span,
 details.rustdoc-toggle > summary::before,
diff --git a/src/librustdoc/html/static/eye-slash.svg b/src/librustdoc/html/static/eye-slash.svg
new file mode 100644
index 0000000000000..9703016791d37
--- /dev/null
+++ b/src/librustdoc/html/static/eye-slash.svg
@@ -0,0 +1 @@
+<?xml version="1.0" ?><svg height="1792" viewBox="0 0 1792 1792" width="1792" xmlns="http://www.w3.org/2000/svg"><path d="M555 1335l78-141q-87-63-136-159t-49-203q0-121 61-225-229 117-381 353 167 258 427 375zm389-759q0-20-14-34t-34-14q-125 0-214.5 89.5t-89.5 214.5q0 20 14 34t34 14 34-14 14-34q0-86 61-147t147-61q20 0 34-14t14-34zm363-191q0 7-1 9-105 188-315 566t-316 567l-49 89q-10 16-28 16-12 0-134-70-16-10-16-28 0-12 44-87-143-65-263.5-173t-208.5-245q-20-31-20-69t20-69q153-235 380-371t496-136q89 0 180 17l54-97q10-16 28-16 5 0 18 6t31 15.5 33 18.5 31.5 18.5 19.5 11.5q16 10 16 27zm37 447q0 139-79 253.5t-209 164.5l280-502q8 45 8 84zm448 128q0 35-20 69-39 64-109 145-150 172-347.5 267t-419.5 95l74-132q212-18 392.5-137t301.5-307q-115-179-282-294l63-112q95 64 182.5 153t144.5 184q20 34 20 69z"/></svg>
\ No newline at end of file
diff --git a/src/librustdoc/html/static/eye.svg b/src/librustdoc/html/static/eye.svg
new file mode 100644
index 0000000000000..7e1d640cced14
--- /dev/null
+++ b/src/librustdoc/html/static/eye.svg
@@ -0,0 +1 @@
+<?xml version="1.0" ?><svg height="1792" viewBox="0 0 1792 1792" width="1792" xmlns="http://www.w3.org/2000/svg"><path d="M1664 960q-152-236-381-353 61 104 61 225 0 185-131.5 316.5t-316.5 131.5-316.5-131.5-131.5-316.5q0-121 61-225-229 117-381 353 133 205 333.5 326.5t434.5 121.5 434.5-121.5 333.5-326.5zm-720-384q0-20-14-34t-34-14q-125 0-214.5 89.5t-89.5 214.5q0 20 14 34t34 14 34-14 14-34q0-86 61-147t147-61q20 0 34-14t14-34zm848 384q0 34-20 69-140 230-376.5 368.5t-499.5 138.5-499.5-139-376.5-368q-20-35-20-69t20-69q140-229 376.5-368t499.5-139 499.5 139 376.5 368q20 35 20 69z"/></svg>
\ No newline at end of file
diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index 1eebd39256459..407b367115a92 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -822,41 +822,50 @@ function hideThemeButtonState() {
         }
     }());
 
-    (function() {
-        // To avoid checking on "rustdoc-line-numbers" value on every loop...
-        var lineNumbersFunc = function() {};
-        if (getSettingValue("line-numbers") === "true") {
-            lineNumbersFunc = function(x) {
-                var count = x.textContent.split("\n").length;
-                var elems = [];
-                for (var i = 0; i < count; ++i) {
-                    elems.push(i + 1);
+    // To avoid checking on "rustdoc-line-numbers" value on every loop...
+    var lineNumbersFunc = function() {};
+    if (getSettingValue("line-numbers") === "true") {
+        lineNumbersFunc = function(x) {
+            var count = 0;
+            var last = "";
+            onEachLazy(x.getElementsByTagName("code")[0].childNodes, function(e) {
+                if (e.nodeType !== Node.TEXT_NODE && hasClass(e, "hidden")) {
+                    return;
                 }
-                var node = document.createElement("pre");
-                addClass(node, "line-number");
-                node.innerHTML = elems.join("\n");
-                x.parentNode.insertBefore(node, x);
-            };
-        }
-        onEachLazy(document.getElementsByClassName("rust-example-rendered"), function(e) {
-            if (hasClass(e, "compile_fail")) {
-                e.addEventListener("mouseover", function() {
-                    this.parentElement.previousElementSibling.childNodes[0].style.color = "#f00";
-                });
-                e.addEventListener("mouseout", function() {
-                    this.parentElement.previousElementSibling.childNodes[0].style.color = "";
-                });
-            } else if (hasClass(e, "ignore")) {
-                e.addEventListener("mouseover", function() {
-                    this.parentElement.previousElementSibling.childNodes[0].style.color = "#ff9200";
-                });
-                e.addEventListener("mouseout", function() {
-                    this.parentElement.previousElementSibling.childNodes[0].style.color = "";
-                });
+                count += e.textContent.split("\n").length - 1;
+                last = e.textContent;
+            });
+            if (!last.endsWith("\n")) {
+                count += 1;
             }
-            lineNumbersFunc(e);
-        });
-    }());
+            var elems = [];
+            for (var i = 0; i < count; ++i) {
+                elems.push(i + 1);
+            }
+            var node = document.createElement("pre");
+            addClass(node, "line-number");
+            node.innerHTML = elems.join("\n");
+            x.parentNode.insertBefore(node, x);
+        };
+    }
+    onEachLazy(document.getElementsByClassName("rust-example-rendered"), function(e) {
+        if (hasClass(e, "compile_fail")) {
+            e.addEventListener("mouseover", function() {
+                this.parentElement.previousElementSibling.childNodes[0].style.color = "#f00";
+            });
+            e.addEventListener("mouseout", function() {
+                this.parentElement.previousElementSibling.childNodes[0].style.color = "";
+            });
+        } else if (hasClass(e, "ignore")) {
+            e.addEventListener("mouseover", function() {
+                this.parentElement.previousElementSibling.childNodes[0].style.color = "#ff9200";
+            });
+            e.addEventListener("mouseout", function() {
+                this.parentElement.previousElementSibling.childNodes[0].style.color = "";
+            });
+        }
+        lineNumbersFunc(e);
+    });
 
     function handleClick(id, f) {
         var elem = document.getElementById(id);
@@ -970,60 +979,135 @@ function hideThemeButtonState() {
     onHashChange(null);
     window.addEventListener("hashchange", onHashChange);
     searchState.setup();
-}());
 
-(function () {
-    var reset_button_timeout = null;
+    (function () {
+        var buttons_timeout = new WeakMap();
+
+        function copyContentToClipboard(content) {
+            var el = document.createElement('textarea');
+            el.value = content;
+            el.setAttribute('readonly', '');
+            // To not make it appear on the screen.
+            el.style.position = 'absolute';
+            el.style.left = '-9999px';
+
+            document.body.appendChild(el);
+            el.select();
+            document.execCommand('copy');
+            document.body.removeChild(el);
+        }
+
+        window.copy_path = function(but) {
+            var parent = but.parentElement;
+            var path = [];
+
+            onEach(parent.childNodes, function(child) {
+                if (child.tagName === 'A') {
+                    path.push(child.textContent);
+                }
+            });
+
+            copyContentToClipboard(path.join('::'));
+
+            // There is always one children, but multiple childNodes.
+            but.children[0].style.display = 'none';
+
+            var tmp;
+            if (but.childNodes.length < 2) {
+                tmp = document.createTextNode('✓');
+                but.appendChild(tmp);
+            } else {
+                onEachLazy(but.childNodes, function(e) {
+                    if (e.nodeType === Node.TEXT_NODE) {
+                        tmp = e;
+                        return true;
+                    }
+                });
+                tmp.textContent = '✓';
+            }
 
-    window.copy_path = function(but) {
-        var parent = but.parentElement;
-        var path = [];
+            if (buttons_timeout.has(but)) {
+                window.clearTimeout(buttons_timeout.get(but));
+            }
 
-        onEach(parent.childNodes, function(child) {
-            if (child.tagName === 'A') {
-                path.push(child.textContent);
+            function reset_button() {
+                tmp.textContent = '';
+                buttons_timeout.delete(but);
+                but.children[0].style.display = "";
             }
-        });
 
-        var el = document.createElement('textarea');
-        el.value = path.join('::');
-        el.setAttribute('readonly', '');
-        // To not make it appear on the screen.
-        el.style.position = 'absolute';
-        el.style.left = '-9999px';
-
-        document.body.appendChild(el);
-        el.select();
-        document.execCommand('copy');
-        document.body.removeChild(el);
-
-        // There is always one children, but multiple childNodes.
-        but.children[0].style.display = 'none';
-
-        var tmp;
-        if (but.childNodes.length < 2) {
-            tmp = document.createTextNode('✓');
-            but.appendChild(tmp);
-        } else {
-            onEachLazy(but.childNodes, function(e) {
-                if (e.nodeType === Node.TEXT_NODE) {
-                    tmp = e;
-                    return true;
+            buttons_timeout.set(but, window.setTimeout(reset_button, 1000));
+        };
+
+        // This part is for the code blocks buttons.
+        window.copyCode = function(but) {
+            var code = but.parentElement.previousElementSibling;
+            var text = "";
+            onEachLazy(code.childNodes, function(e) {
+                if (e.nodeType !== Node.TEXT_NODE && hasClass(e, "hidden")) {
+                    return;
                 }
+                text += e.textContent;
             });
-            tmp.textContent = '✓';
-        }
 
-        if (reset_button_timeout !== null) {
-            window.clearTimeout(reset_button_timeout);
-        }
+            copyContentToClipboard(text);
+
+            removeClass(but, 'clicked');
+            addClass(but, 'clicked');
 
-        function reset_button() {
-            tmp.textContent = '';
-            reset_button_timeout = null;
-            but.children[0].style.display = "";
+            if (buttons_timeout.has(but)) {
+                window.clearTimeout(buttons_timeout.get(but));
+            }
+
+            var tmp;
+            if (but.childNodes.length < 1) {
+                tmp = document.createTextNode('✓');
+                but.appendChild(tmp);
+            } else {
+                tmp = but.childNodes[0];
+                tmp.textContent = '✓';
+            }
+            but.style.backgroundSize = '0';
+
+            if (buttons_timeout.has(but)) {
+                window.clearTimeout(buttons_timeout.get(but));
+            }
+
+            function reset_button() {
+                but.style.backgroundSize = '';
+                tmp.textContent = '';
+                buttons_timeout.delete(but);
+            }
+
+            buttons_timeout.set(but, window.setTimeout(reset_button, 1000));
+        };
+
+        function removeLineNumbers(but) {
+            onEachLazy(but.getElementsByClassName("line-number"), function(e) {
+                e.parentElement.removeChild(e);
+            });
         }
 
-        reset_button_timeout = window.setTimeout(reset_button, 1000);
-    };
+        window.expandCode = function(but) {
+            var code = but.parentElement.previousElementSibling;
+            if (hasClass(but, "expand")) {
+                onEachLazy(code.getElementsByClassName("hidden"), function(e) {
+                    removeClass(e, "hidden");
+                    addClass(e, "data-hidden");
+                });
+                removeClass(but, "expand");
+                addClass(but, "collapse");
+            } else {
+                onEachLazy(code.getElementsByClassName("data-hidden"), function(e) {
+                    removeClass(e, "data-hidden");
+                    addClass(e, "hidden");
+                });
+                removeClass(but, "collapse");
+                addClass(but, "expand");
+            }
+            // We recompute the line numbers display.
+            removeLineNumbers(code.parentElement);
+            lineNumbersFunc(code);
+        };
+    }());
 }());
diff --git a/src/librustdoc/html/static_files.rs b/src/librustdoc/html/static_files.rs
index 6f3d08ea65569..e63537f2d1a57 100644
--- a/src/librustdoc/html/static_files.rs
+++ b/src/librustdoc/html/static_files.rs
@@ -53,6 +53,12 @@ crate static TOGGLE_MINUS_PNG: &[u8] = include_bytes!("static/images/toggle-minu
 /// The file contents of `toggle-plus.svg`, the icon used for closed toggles.
 crate static TOGGLE_PLUS_PNG: &[u8] = include_bytes!("static/images/toggle-plus.svg");
 
+/// The file contents of `expand.svg`, the icon used to show hidden code blocks lines.
+crate static EXPAND_SVG: &[u8] = include_bytes!("static/eye.svg");
+
+/// The file contents of `collapse.svg`, the icon used to collapse hidden code blocks lines.
+crate static COLLAPSE_SVG: &[u8] = include_bytes!("static/eye-slash.svg");
+
 /// The contents of `COPYRIGHT.txt`, the license listing for files distributed with documentation
 /// output.
 crate static COPYRIGHT: &[u8] = include_bytes!("static/COPYRIGHT.txt");
diff --git a/src/test/rustdoc-gui/code_block_lines.goml b/src/test/rustdoc-gui/code_block_lines.goml
new file mode 100644
index 0000000000000..ad07fba3814a1
--- /dev/null
+++ b/src/test/rustdoc-gui/code_block_lines.goml
@@ -0,0 +1,30 @@
+goto: file://|DOC_PATH|/lib2/trait.Trait.html
+// We set the parameter to display line numbers on code blocks.
+local-storage: {"rustdoc-line-numbers": "true"}
+// We reload the page so they're displayed.
+reload:
+wait-for: ".line-number"
+assert: ".top-doc .line-number"
+assert-text: (".top-doc .line-number", "1\n2\n3\n4")
+// We check that the hidden content is present
+assert: ".top-doc .rust-example-rendered span.hidden"
+assert-text: (".top-doc .rust-example-rendered span.hidden", "fn main() {\n")
+assert-text: (".methods .line-number", "1\n2\n3\n4\n5\n6\n7")
+
+// Now we check the collapse/expand feature.
+assert: ".top-doc .expand"
+assert-false: ".top-doc .collapse"
+click: ".top-doc .expand"
+assert-text: (".top-doc .line-number", "1\n2\n3\n4\n5\n6\n7")
+assert: ".top-doc .collapse"
+assert-false: ".top-doc .expand"
+click: ".top-doc .collapse"
+assert-text: (".top-doc .line-number", "1\n2\n3\n4")
+assert: ".top-doc .expand"
+assert-false: ".top-doc .collapse"
+// We now check that the button isn't present if there is no hidden lines.
+assert-false: ".methods .expand"
+assert-false: ".methods .collapse"
+
+// We unset the parameter to be sure it won't affect other tests.
+local-storage: {"rustdoc-line-numbers": ""}
diff --git a/src/test/rustdoc-gui/src/lib2/lib.rs b/src/test/rustdoc-gui/src/lib2/lib.rs
index d5835b78d2fcf..a07aa6fdf75f5 100644
--- a/src/test/rustdoc-gui/src/lib2/lib.rs
+++ b/src/test/rustdoc-gui/src/lib2/lib.rs
@@ -25,10 +25,30 @@ impl Foo {
     pub fn a_method(&self) {}
 }
 
+// This is used to ensure the line numbers are correctly set.
+/// ```
+/// # fn main() {
+/// let x = 12;
+/// let y = 13;
+/// # let z = 14;
+///
+/// println!("hello");
+/// # }
+/// ```
 pub trait Trait {
     type X;
     const Y: u32;
 
+    // This is used to ensure the line numbers are correctly set.
+    /// ```
+    /// fn main() {
+    /// let x = 12;
+    /// let y = 13;
+    /// let z = 14;
+    ///
+    /// println!("hello");
+    /// }
+    /// ```
     fn foo() {}
 }
 
diff --git a/src/test/rustdoc/hidden-line.rs b/src/test/rustdoc/hidden-line.rs
index f2f6173d26db9..3d89122655199 100644
--- a/src/test/rustdoc/hidden-line.rs
+++ b/src/test/rustdoc/hidden-line.rs
@@ -15,5 +15,7 @@
 /// ```
 pub fn foo() {}
 
-// @!has hidden_line/fn.foo.html invisible
+// @has hidden_line/fn.foo.html
+// @has - '//span[@class="hidden"]' '#[derive(PartialEq)] // invisible'
+// @has - '//span[@class="hidden"]' 'struct Foo; // invisible'
 // @matches - //pre "#\[derive\(PartialEq\)\] // Bar"
diff --git a/src/test/rustdoc/issue-41783.rs b/src/test/rustdoc/issue-41783.rs
index cb9b9b1538951..b026c47ef6b09 100644
--- a/src/test/rustdoc/issue-41783.rs
+++ b/src/test/rustdoc/issue-41783.rs
@@ -1,6 +1,6 @@
 // @has issue_41783/struct.Foo.html
-// @!has - 'space'
-// @!has - 'comment'
+// @has - '//span[@class="hidden"]' 'space'
+// @has - '//span[@class="hidden"]' 'comment'
 // @has - '# <span class="ident">single'
 // @has - '## <span class="ident">double</span>'
 // @has - '### <span class="ident">triple</span>'