diff --git a/README.md b/README.md
index f35631c..6a5626d 100644
--- a/README.md
+++ b/README.md
@@ -10,8 +10,9 @@
 - [x] Transfer-Encoding: chunked
 - [x] Ergonomic JSON handling
 - [x] Test harness for end-to-end tests
-- [ ] Limit read length on Content-Size
-- [ ] Auth headers
+- [x] Limit read length on Content-Size
+- [x] Auth headers
+- [x] Repeated headers
 - [ ] Cookie jar in agent
 - [ ] Forms with application/x-www-form-urlencoded
 - [ ] multipart/form-data
diff --git a/src/agent.rs b/src/agent.rs
index c77cf53..43bc5ba 100644
--- a/src/agent.rs
+++ b/src/agent.rs
@@ -53,7 +53,9 @@ impl Agent {
         K: Into<String>,
         V: Into<String>,
     {
-        add_agent_header(self, header.into(), value.into());
+        let s = format!("{}: {}", header.into(), value.into());
+        let header = s.parse::<Header>().expect("Failed to parse header");
+        add_header(header, &mut self.headers);
         self
     }
 
@@ -87,7 +89,9 @@ impl Agent {
         I: IntoIterator<Item = (K, V)>,
     {
         for (k, v) in headers.into_iter() {
-            add_agent_header(self, k.into(), v.into());
+            let s = format!("{}: {}", k.into(), v.into());
+            let header = s.parse::<Header>().expect("Failed to parse header");
+            add_header(header, &mut self.headers);
         }
         self
     }
diff --git a/src/header.rs b/src/header.rs
index 81c2900..662d9f6 100644
--- a/src/header.rs
+++ b/src/header.rs
@@ -56,3 +56,11 @@ impl FromStr for Header {
         Ok(Header { line, index })
     }
 }
+
+pub fn add_header(header: Header, headers: &mut Vec<Header>) {
+    if !header.name().to_lowercase().starts_with("x-") {
+        let name = header.name();
+        headers.retain(|h| h.name() != name);
+    }
+    headers.push(header);
+}
diff --git a/src/request.rs b/src/request.rs
index 0232bad..38fb915 100644
--- a/src/request.rs
+++ b/src/request.rs
@@ -177,7 +177,9 @@ impl Request {
         K: Into<String>,
         V: Into<String>,
     {
-        add_request_header(self, header.into(), value.into());
+        let s = format!("{}: {}", header.into(), value.into());
+        let header = s.parse::<Header>().expect("Failed to parse header");
+        add_header(header, &mut self.headers);
         self
     }
 
@@ -208,6 +210,26 @@ impl Request {
         self.get(name).is_some()
     }
 
+    /// All headers corresponding values for the give name, or empty vector.
+    ///
+    /// ```
+    /// let req = ureq::get("/my_page")
+    ///     .set("X-Forwarded-For", "1.2.3.4")
+    ///     .set("X-Forwarded-For", "2.3.4.5")
+    ///     .build();
+    /// assert_eq!(req.get_all("x-forwarded-for"), vec![
+    ///     "1.2.3.4",
+    ///     "2.3.4.5",
+    /// ]);
+    /// ```
+    pub fn get_all<'a>(&self, name: &'a str) -> Vec<&str> {
+        self.headers
+            .iter()
+            .filter(|h| h.is_name(name))
+            .map(|h| h.value())
+            .collect()
+    }
+
     /// Set many headers.
     ///
     /// ```
@@ -234,7 +256,9 @@ impl Request {
         I: IntoIterator<Item = (K, V)>,
     {
         for (k, v) in headers.into_iter() {
-            add_request_header(self, k.into(), v.into());
+            let s = format!("{}: {}", k.into(), v.into());
+            let header = s.parse::<Header>().expect("Failed to parse header");
+            add_header(header, &mut self.headers);
         }
         self
     }
diff --git a/src/test/simple.rs b/src/test/simple.rs
index cf1e16e..e6259ea 100644
--- a/src/test/simple.rs
+++ b/src/test/simple.rs
@@ -16,6 +16,38 @@ fn header_passing() {
     assert_eq!(resp.get("X-Bar").unwrap(), "foo");
 }
 
+#[test]
+fn repeat_non_x_header() {
+    test::set_handler("/repeat_non_x_header", |req, _url| {
+        assert!(req.has("Accept"));
+        assert_eq!(req.get("Accept").unwrap(), "baz");
+        test::make_stream(200, "OK", vec![], vec![])
+    });
+    let resp = get("test://host/repeat_non_x_header")
+        .set("Accept", "bar")
+        .set("Accept", "baz")
+        .call();
+    assert_eq!(*resp.status(), 200);
+}
+
+#[test]
+fn repeat_x_header() {
+    test::set_handler("/repeat_x_header", |req, _url| {
+        assert!(req.has("X-Forwarded-For"));
+        assert_eq!(req.get("X-Forwarded-For").unwrap(), "130.240.19.2");
+        assert_eq!(req.get_all("X-Forwarded-For"), vec![
+            "130.240.19.2",
+            "130.240.19.3",
+        ]);
+        test::make_stream(200, "OK", vec![], vec![])
+    });
+    let resp = get("test://host/repeat_x_header")
+        .set("X-Forwarded-For", "130.240.19.2")
+        .set("X-Forwarded-For", "130.240.19.3")
+        .call();
+    assert_eq!(*resp.status(), 200);
+}
+
 #[test]
 fn body_as_text() {
     test::set_handler("/body_as_text", |_req, _url| {