diff --git a/Documentation/gitattributes.adoc b/Documentation/gitattributes.adoc
index bd76167a45..9fea75f96f 100644
--- a/Documentation/gitattributes.adoc
+++ b/Documentation/gitattributes.adoc
@@ -914,6 +914,8 @@ patterns are available:
 - `scheme` suitable for source code in most Lisp dialects,
   including Scheme, Emacs Lisp, Common Lisp, and Clojure.
 
+- `swift` suitable for source code in the Swift language.
+
 - `tex` suitable for source code for LaTeX documents.
 
 
diff --git a/t/t4018/swift-actor b/t/t4018/swift-actor
new file mode 100644
index 0000000000..e4852f40a7
--- /dev/null
+++ b/t/t4018/swift-actor
@@ -0,0 +1,5 @@
+actor RIGHT {
+    let a = 1
+    // a comment
+    let b = ChangeMe
+}
diff --git a/t/t4018/swift-attribute-with-args b/t/t4018/swift-attribute-with-args
new file mode 100644
index 0000000000..22b1ee32f1
--- /dev/null
+++ b/t/t4018/swift-attribute-with-args
@@ -0,0 +1,7 @@
+struct View {
+    @available(iOS 13, *) public func RIGHT() {
+        let a = 1
+        // a comment
+        print(ChangeMe)
+    }
+}
diff --git a/t/t4018/swift-class b/t/t4018/swift-class
new file mode 100644
index 0000000000..c3a9336027
--- /dev/null
+++ b/t/t4018/swift-class
@@ -0,0 +1,5 @@
+class RIGHT {
+    let a = 1
+    // a comment
+    let b = ChangeMe
+}
diff --git a/t/t4018/swift-enum b/t/t4018/swift-enum
new file mode 100644
index 0000000000..0a84302993
--- /dev/null
+++ b/t/t4018/swift-enum
@@ -0,0 +1,5 @@
+enum RIGHT {
+    case first
+    // a comment
+    case ChangeMe
+}
diff --git a/t/t4018/swift-extension b/t/t4018/swift-extension
new file mode 100644
index 0000000000..cbc18ab6ef
--- /dev/null
+++ b/t/t4018/swift-extension
@@ -0,0 +1,5 @@
+extension RIGHT {
+    static let a = 1
+    // a comment
+    static let b = ChangeMe
+}
diff --git a/t/t4018/swift-failable-init b/t/t4018/swift-failable-init
new file mode 100644
index 0000000000..4bbd6217c9
--- /dev/null
+++ b/t/t4018/swift-failable-init
@@ -0,0 +1,7 @@
+class Bar {
+    init?(RIGHT: Int) {
+        let x = 0
+        // a comment
+        print(ChangeMe)
+    }
+}
diff --git a/t/t4018/swift-func b/t/t4018/swift-func
new file mode 100644
index 0000000000..1fecae0911
--- /dev/null
+++ b/t/t4018/swift-func
@@ -0,0 +1,5 @@
+func RIGHT(x: Int) -> Int {
+    let y = x
+    // a comment
+    return ChangeMe
+}
diff --git a/t/t4018/swift-generic-subscript b/t/t4018/swift-generic-subscript
new file mode 100644
index 0000000000..423cb58941
--- /dev/null
+++ b/t/t4018/swift-generic-subscript
@@ -0,0 +1,7 @@
+struct Container {
+    subscript<RIGHT>(index: Int) -> Int {
+        let a = 0
+        // a comment
+        return ChangeMe
+    }
+}
diff --git a/t/t4018/swift-init b/t/t4018/swift-init
new file mode 100644
index 0000000000..dc7a298f38
--- /dev/null
+++ b/t/t4018/swift-init
@@ -0,0 +1,7 @@
+class Foo {
+    init(RIGHT: Int) {
+        let x = 0
+        // a comment
+        print(ChangeMe)
+    }
+}
diff --git a/t/t4018/swift-inline-attribute b/t/t4018/swift-inline-attribute
new file mode 100644
index 0000000000..2374c4b603
--- /dev/null
+++ b/t/t4018/swift-inline-attribute
@@ -0,0 +1,7 @@
+class Service {
+    @objc func RIGHT() {
+        let path = "/api"
+        // a comment
+        log(ChangeMe)
+    }
+}
diff --git a/t/t4018/swift-modifiers b/t/t4018/swift-modifiers
new file mode 100644
index 0000000000..9d80685a78
--- /dev/null
+++ b/t/t4018/swift-modifiers
@@ -0,0 +1,4 @@
+public static func RIGHT() -> Int {
+    // a comment
+    return ChangeMe
+}
diff --git a/t/t4018/swift-protocol b/t/t4018/swift-protocol
new file mode 100644
index 0000000000..07c39ec2a3
--- /dev/null
+++ b/t/t4018/swift-protocol
@@ -0,0 +1,5 @@
+protocol RIGHT {
+    var first: Int { get }
+    // a comment
+    var second: ChangeMe { get }
+}
diff --git a/t/t4018/swift-struct b/t/t4018/swift-struct
new file mode 100644
index 0000000000..e399ed7759
--- /dev/null
+++ b/t/t4018/swift-struct
@@ -0,0 +1,5 @@
+struct RIGHT {
+    let a = 1
+    // a comment
+    let b = ChangeMe
+}
diff --git a/userdiff.c b/userdiff.c
index b5412e6bc3..7129bf1482 100644
--- a/userdiff.c
+++ b/userdiff.c
@@ -362,6 +362,16 @@ PATTERNS("scheme",
 	 "\\|([^|\\\\]|\\\\.)*\\|"
 	 /* All other words should be delimited by spaces or parentheses. */
 	 "|([^][)(}{ \t])+"),
+PATTERNS("swift",
+	 "^[ \t]*((@[A-Za-z_][A-Za-z0-9_]*(\\([^()]*\\))?[ \t]+)*([a-z]+[ \t]+)*(func|init|deinit|subscript|class|struct|enum|protocol|extension|actor)[ \t(?!<].*)$",
+	 /* -- */
+	 "[a-zA-Z_][a-zA-Z0-9_]*"
+	 /* hexadecimal, octal, and binary literals */
+	 "|0[xX][0-9a-fA-F_]+|0[oO][0-7_]+|0[bB][01_]+"
+	 /* integers and floating-point numbers */
+	 "|[0-9][0-9_]*([.][0-9_]+)?([eE][-+]?[0-9]+)?"
+	 /* unary and binary operators */
+	 "|[-+*/%<>=!&|^~?]=|&&|\\|\\||<<=?|>>=?|\\?\\?|\\.\\.[.<]|->"),
 PATTERNS("tex", "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$",
 	 "\\\\[a-zA-Z@]+|\\\\.|([a-zA-Z0-9]|[^\x01-\x7f])+"),
 { .name = "default", .binary = -1 },