diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 7d116f23ef581..935b690497b52 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -306,7 +306,7 @@ impl<'a> Builder<'a> {
             Subcommand::Bench { ref paths, .. } => (Kind::Bench, &paths[..]),
             Subcommand::Dist { ref paths } => (Kind::Dist, &paths[..]),
             Subcommand::Install { ref paths } => (Kind::Install, &paths[..]),
-            Subcommand::Clean => panic!(),
+            Subcommand::Clean { .. } => panic!(),
         };
 
         let builder = Builder {
diff --git a/src/bootstrap/clean.rs b/src/bootstrap/clean.rs
index 119340a0190c4..87f194fb7d2f8 100644
--- a/src/bootstrap/clean.rs
+++ b/src/bootstrap/clean.rs
@@ -13,7 +13,7 @@
 //! Responsible for cleaning out a build directory of all old and stale
 //! artifacts to prepare for a fresh build. Currently doesn't remove the
 //! `build/cache` directory (download cache) or the `build/$target/llvm`
-//! directory as we want that cached between builds.
+//! directory unless the --all flag is present.
 
 use std::fs;
 use std::io::{self, ErrorKind};
@@ -21,24 +21,29 @@ use std::path::Path;
 
 use Build;
 
-pub fn clean(build: &Build) {
+pub fn clean(build: &Build, all: bool) {
     rm_rf("tmp".as_ref());
-    rm_rf(&build.out.join("tmp"));
-    rm_rf(&build.out.join("dist"));
 
-    for host in &build.hosts {
-        let entries = match build.out.join(host).read_dir() {
-            Ok(iter) => iter,
-            Err(_) => continue,
-        };
+    if all {
+        rm_rf(&build.out);
+    } else {
+        rm_rf(&build.out.join("tmp"));
+        rm_rf(&build.out.join("dist"));
 
-        for entry in entries {
-            let entry = t!(entry);
-            if entry.file_name().to_str() == Some("llvm") {
-                continue
+        for host in &build.hosts {
+            let entries = match build.out.join(host).read_dir() {
+                Ok(iter) => iter,
+                Err(_) => continue,
+            };
+
+            for entry in entries {
+                let entry = t!(entry);
+                if entry.file_name().to_str() == Some("llvm") {
+                    continue
+                }
+                let path = t!(entry.path().canonicalize());
+                rm_rf(&path);
             }
-            let path = t!(entry.path().canonicalize());
-            rm_rf(&path);
         }
     }
 }
diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index 7546d7fd4f07a..df378188b4ad0 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -60,7 +60,9 @@ pub enum Subcommand {
         paths: Vec<PathBuf>,
         test_args: Vec<String>,
     },
-    Clean,
+    Clean {
+        all: bool,
+    },
     Dist {
         paths: Vec<PathBuf>,
     },
@@ -147,6 +149,7 @@ To learn more about a subcommand, run `./x.py <subcommand> -h`");
                 opts.optmulti("", "test-args", "extra arguments", "ARGS");
             },
             "bench" => { opts.optmulti("", "test-args", "extra arguments", "ARGS"); },
+            "clean" => { opts.optflag("", "all", "clean all build artifacts"); },
             _ => { },
         };
 
@@ -250,7 +253,7 @@ Arguments:
             }
         });
 
-        // All subcommands can have an optional "Available paths" section
+        // All subcommands except `clean` can have an optional "Available paths" section
         if matches.opt_present("verbose") {
             let config = Config::parse(&["build".to_string()]);
             let mut build = Build::new(config);
@@ -258,9 +261,10 @@ Arguments:
 
             let maybe_rules_help = Builder::get_help(&build, subcommand.as_str());
             extra_help.push_str(maybe_rules_help.unwrap_or_default().as_str());
-        } else {
-            extra_help.push_str(format!("Run `./x.py {} -h -v` to see a list of available paths.",
-                     subcommand).as_str());
+        } else if subcommand.as_str() != "clean" {
+            extra_help.push_str(format!(
+                "Run `./x.py {} -h -v` to see a list of available paths.",
+                subcommand).as_str());
         }
 
         // User passed in -h/--help?
@@ -290,10 +294,13 @@ Arguments:
             }
             "clean" => {
                 if paths.len() > 0 {
-                    println!("\nclean takes no arguments\n");
+                    println!("\nclean does not take a path argument\n");
                     usage(1, &opts, &subcommand_help, &extra_help);
                 }
-                Subcommand::Clean
+
+                Subcommand::Clean {
+                    all: matches.opt_present("all"),
+                }
             }
             "dist" => {
                 Subcommand::Dist {
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 06c7c4c2faffc..0876786f9a544 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -345,8 +345,8 @@ impl Build {
             job::setup(self);
         }
 
-        if let Subcommand::Clean = self.config.cmd {
-            return clean::clean(self);
+        if let Subcommand::Clean { all } = self.config.cmd {
+            return clean::clean(self, all);
         }
 
         self.verbose("finding compilers");