diff --git a/src/bin/main.rs b/src/bin/main.rs
index 3ad2d3088f0..34c1bc59745 100644
--- a/src/bin/main.rs
+++ b/src/bin/main.rs
@@ -15,7 +15,7 @@ extern crate getopts;
 extern crate rustfmt_nightly as rustfmt;
 
 use std::fs::File;
-use std::io::{self, Read, Write};
+use std::io::{self, stdout, Read, Write};
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use std::{env, error};
@@ -226,7 +226,7 @@ fn execute(opts: &Options) -> FmtResult<Summary> {
             Ok(Summary::default())
         }
         Operation::ConfigHelp => {
-            Config::print_docs();
+            Config::print_docs(&mut stdout(), matches.opt_present("unstable-features"));
             Ok(Summary::default())
         }
         Operation::ConfigOutputDefault { path } => {
diff --git a/src/config/config_type.rs b/src/config/config_type.rs
index 53a4fdb8e57..0c38b6d28ad 100644
--- a/src/config/config_type.rs
+++ b/src/config/config_type.rs
@@ -81,6 +81,7 @@ macro_rules! is_nightly_channel {
 macro_rules! create_config {
     ($($i:ident: $ty:ty, $def:expr, $stb:expr, $( $dstring:expr ),+ );+ $(;)*) => (
         use std::collections::HashSet;
+        use std::io::Write;
 
         #[derive(Clone)]
         pub struct Config {
@@ -359,7 +360,7 @@ macro_rules! create_config {
                 HIDE_OPTIONS.contains(&name)
             }
 
-            pub fn print_docs() {
+            pub fn print_docs(out: &mut Write, include_unstable: bool) {
                 use std::cmp;
                 let max = 0;
                 $( let max = cmp::max(max, stringify!($i).len()+1); )+
@@ -367,25 +368,29 @@ macro_rules! create_config {
                 for _ in 0..max {
                     space_str.push(' ');
                 }
-                println!("Configuration Options:");
+                writeln!(out, "Configuration Options:").unwrap();
                 $(
-                    let name_raw = stringify!($i);
+                    if $stb || include_unstable {
+                        let name_raw = stringify!($i);
 
-                    if !Config::is_hidden_option(name_raw) {
-                        let mut name_out = String::with_capacity(max);
-                        for _ in name_raw.len()..max-1 {
-                            name_out.push(' ')
+                        if !Config::is_hidden_option(name_raw) {
+                            let mut name_out = String::with_capacity(max);
+                            for _ in name_raw.len()..max-1 {
+                                name_out.push(' ')
+                            }
+                            name_out.push_str(name_raw);
+                            name_out.push(' ');
+                            writeln!(out,
+                                    "{}{} Default: {:?}{}",
+                                    name_out,
+                                    <$ty>::doc_hint(),
+                                    $def,
+                                    if !$stb { " (unstable)" } else { "" }).unwrap();
+                            $(
+                                writeln!(out, "{}{}", space_str, $dstring).unwrap();
+                            )+
+                            writeln!(out).unwrap();
                         }
-                        name_out.push_str(name_raw);
-                        name_out.push(' ');
-                        println!("{}{} Default: {:?}",
-                                name_out,
-                                <$ty>::doc_hint(),
-                                $def);
-                        $(
-                            println!("{}{}", space_str, $dstring);
-                        )+
-                        println!();
                     }
                 )+
             }
diff --git a/src/config/mod.rs b/src/config/mod.rs
index 7b96c2f671e..3676aed4ba9 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -181,6 +181,31 @@ pub fn get_toml_path(dir: &Path) -> Result<Option<PathBuf>, Error> {
 #[cfg(test)]
 mod test {
     use super::Config;
+    use std::str;
+
+    #[allow(dead_code)]
+    mod mock {
+        use super::super::*;
+
+        create_config! {
+            // Options that are used by the generated functions
+            max_width: usize, 100, true, "Maximum width of each line";
+            use_small_heuristics: bool, true, false, "Whether to use different formatting for items and \
+                expressions if they satisfy a heuristic notion of 'small'.";
+            license_template_path: String, String::default(), false, "Beginning of file must match license template";
+            required_version: String, env!("CARGO_PKG_VERSION").to_owned(), false, "Require a specific version of rustfmt.";
+            ignore: IgnoreList, IgnoreList::default(), false, "Skip formatting the specified files and directories.";
+            verbose: bool, false, false, "Use verbose output";
+            file_lines: FileLines, FileLines::all(), false,
+                "Lines to format; this is not supported in rustfmt.toml, and can only be specified \
+                    via the --file-lines option";
+            width_heuristics: WidthHeuristics, WidthHeuristics::scaled(100), false, "'small' heuristic values";
+
+            // Options that are used by the tests
+            stable_option: bool, false, true, "A stable option";
+            unstable_option: bool, false, false, "An unstable option";
+        }
+    }
 
     #[test]
     fn test_config_set() {
@@ -218,6 +243,33 @@ mod test {
         assert_eq!(config.was_set().verbose(), false);
     }
 
+    #[test]
+    fn test_print_docs_exclude_unstable() {
+        use self::mock::Config;
+
+        let mut output = Vec::new();
+        Config::print_docs(&mut output, false);
+
+        let s = str::from_utf8(&output).unwrap();
+
+        assert_eq!(s.contains("stable_option"), true);
+        assert_eq!(s.contains("unstable_option"), false);
+        assert_eq!(s.contains("(unstable)"), false);
+    }
+
+    #[test]
+    fn test_print_docs_include_unstable() {
+        use self::mock::Config;
+
+        let mut output = Vec::new();
+        Config::print_docs(&mut output, true);
+
+        let s = str::from_utf8(&output).unwrap();
+        assert_eq!(s.contains("stable_option"), true);
+        assert_eq!(s.contains("unstable_option"), true);
+        assert_eq!(s.contains("(unstable)"), true);
+    }
+
     // FIXME(#2183) these tests cannot be run in parallel because they use env vars
     // #[test]
     // fn test_as_not_nightly_channel() {