diff --git a/layout/reftests/text/hyphenation-control-1-ref.html b/layout/reftests/text/hyphenation-control-1-ref.html
new file mode 100644
index 000000000000..57f60bbfd16a
--- /dev/null
+++ b/layout/reftests/text/hyphenation-control-1-ref.html
@@ -0,0 +1,47 @@
+<!DOCTYPE html>
+<html>
+<head>
+<style>
+code {
+  display:block;
+  hyphens:manual;
+  border: 1px solid black;
+}
+</style>
+</head>
+<body lang="en-us">
+<!--
+  Hyphenation opportunities of the texts in this test are as follows,
+
+        frag[A]ilis[A]tic[C]ex[A]pi[A]ali
+
+  where [A] is an automatic hyphen, and [C] is a conditional hyphen.
+
+  In this test, we set width to somewhere between every pair of adjacent hyphenations,
+  then we see if lines break correctly.
+-->
+<code style="width:4ch;">
+frag-<br />ilis-<br />tic-<br />ex-<br />pi-<br />ali
+</code>
+<br />
+<code style="width:5ch;">
+frag-<br />ilis-<br />tic-<br />expi-<br />ali
+</code>
+<br />
+<code style="width:9ch;">
+fragilis-<br />tic-<br />expiali
+</code>
+<br />
+<code style="width:12ch;">
+fragilistic-<br />expiali
+</code>
+<br />
+<code style="width:14ch;">
+fragilistic-<br />expiali
+</code>
+<br />
+<code style="width:16ch;">
+fragilistic-<br />expiali
+</code>
+</body>
+</html>
diff --git a/layout/reftests/text/hyphenation-control-1.html b/layout/reftests/text/hyphenation-control-1.html
new file mode 100644
index 000000000000..31c400c01c7e
--- /dev/null
+++ b/layout/reftests/text/hyphenation-control-1.html
@@ -0,0 +1,47 @@
+<!DOCTYPE html>
+<html>
+<head>
+<style>
+code {
+  display:block;
+  hyphens:auto;
+  border: 1px solid black;
+}
+</style>
+</head>
+<body lang="en-us">
+<!--
+  Hyphenation opportunities of the texts in this test are as follows,
+
+        frag[A]ilis[A]tic[C]ex[A]pi[A]ali
+
+  where [A] is an automatic hyphen, and [C] is a conditional hyphen.
+
+  In this test, we set width to somewhere between every pair of adjacent hyphenations,
+  then we see if lines break correctly.
+-->
+<code style="width:4ch;">
+fragilistic&shy;expiali
+</code>
+<br />
+<code style="width:5ch;">
+fragilistic&shy;expiali
+</code>
+<br />
+<code style="width:9ch;">
+fragilistic&shy;expiali
+</code>
+<br />
+<code style="width:12ch;">
+fragilistic&shy;expiali
+</code>
+<br />
+<code style="width:14ch;">
+fragilistic&shy;expiali
+</code>
+<br />
+<code style="width:16ch;">
+fragilistic&shy;expiali
+</code>
+</body>
+</html>
diff --git a/layout/reftests/text/hyphenation-control-2-ref.html b/layout/reftests/text/hyphenation-control-2-ref.html
new file mode 100644
index 000000000000..6f48c8bd8bd8
--- /dev/null
+++ b/layout/reftests/text/hyphenation-control-2-ref.html
@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<html>
+<head>
+<style>
+code {
+  display:block;
+  hyphens:manual;
+  border: 1px solid black;
+}
+</style>
+</head>
+<body lang="en-us">
+<code style="width:15ch;">
+Supercali-<br />fragilistic-<br />expialidocious
+</code>
+<br />
+<code style="width:15ch;">
+Supercali&#x2010;<br />fragilistic&#x2010;<br />expialidocious
+</code>
+<br />
+</body>
+</html>
diff --git a/layout/reftests/text/hyphenation-control-2.html b/layout/reftests/text/hyphenation-control-2.html
new file mode 100644
index 000000000000..7cbb3ec45746
--- /dev/null
+++ b/layout/reftests/text/hyphenation-control-2.html
@@ -0,0 +1,27 @@
+<!DOCTYPE html>
+<html>
+<head>
+<style>
+code {
+  display:block;
+  hyphens:auto;
+  border: 1px solid black;
+}
+</style>
+</head>
+<body lang="en-us">
+<!--
+  Test checks that automatic hyphenation opportunities within a word
+  must be ignored if the word contains an explicit hyphen (U+2010) or hyphen-minus (U+002D),
+  in favor of the conditional hyphen(s)
+-->
+<code style="width:15ch;">
+Supercali-fragilistic-expialidocious
+</code>
+<br />
+<code style="width:15ch;">
+Supercali&#x2010;fragilistic&#x2010;expialidocious
+</code>
+<br />
+</body>
+</html>
diff --git a/layout/reftests/text/hyphenation-control-3-ref.html b/layout/reftests/text/hyphenation-control-3-ref.html
new file mode 100644
index 000000000000..555c771a4bbc
--- /dev/null
+++ b/layout/reftests/text/hyphenation-control-3-ref.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html>
+<head>
+<style>
+code {
+  display:block;
+  hyphens:manual;
+  border: 1px solid black;
+}
+</style>
+</head>
+<body lang="en-us">
+<code style="width:100ch;">
+ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTU-<br />VWXYZsupercalifragilisticexpialidocious-<br />ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
+</code>
+</body>
+</html>
diff --git a/layout/reftests/text/hyphenation-control-3.html b/layout/reftests/text/hyphenation-control-3.html
new file mode 100644
index 000000000000..845f9a1f46d5
--- /dev/null
+++ b/layout/reftests/text/hyphenation-control-3.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html>
+<head>
+<style>
+code {
+  display:block;
+  hyphens:auto;
+  border: 1px solid black;
+}
+</style>
+</head>
+<body lang="en-us">
+<!--
+  Test checks that automatic hyphenation opportunities should honor
+  manual hyphenation opportunities even if they are within an extreme long word.
+-->
+<code style="width:100ch;">
+ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZsuper&shy;cali&shy;fragi&shy;listic&shy;expiali&shy;docious&shy;ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ
+</code>
+</body>
+</html>
diff --git a/layout/reftests/text/reftest.list b/layout/reftests/text/reftest.list
index 957ec6b692a5..4b21b150d3b0 100644
--- a/layout/reftests/text/reftest.list
+++ b/layout/reftests/text/reftest.list
@@ -316,6 +316,10 @@ HTTP(..) == graphite-surrogate-selection.html graphite-surrogate-selection-ref.h
 
 == auto-hyphenation-transformed-1.html auto-hyphenation-transformed-1-ref.html
 
+== hyphenation-control-1.html hyphenation-control-1-ref.html
+== hyphenation-control-2.html hyphenation-control-2-ref.html
+== hyphenation-control-3.html hyphenation-control-3-ref.html
+
 # osx-font-smoothing - with and without subpixel AA, only under OSX
 fails-if(!cocoaWidget) != osx-font-smoothing.html osx-font-smoothing-ref.html
 fails-if(!cocoaWidget) != osx-font-smoothing-2.html osx-font-smoothing-2-notref.html
