diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 73761b57a8d442196cbeba4c400da236db0482f9..707c1ff3efad93012f7893ebed89731fe52d06f4 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -193,37 +193,37 @@ fn run(v: &[StepDescription], builder: &Builder<'_>, paths: &[PathBuf]) {
             );
         }
 
-        if paths.is_empty() {
-            for (desc, should_run) in v.iter().zip(should_runs) {
+        if paths.is_empty() || builder.config.include_default_paths {
+            for (desc, should_run) in v.iter().zip(&should_runs) {
                 if desc.default && should_run.is_really_default {
                     for pathset in &should_run.paths {
                         desc.maybe_run(builder, pathset);
                     }
                 }
             }
-        } else {
-            for path in paths {
-                // strip CurDir prefix if present
-                let path = match path.strip_prefix(".") {
-                    Ok(p) => p,
-                    Err(_) => path,
-                };
+        }
 
-                let mut attempted_run = false;
-                for (desc, should_run) in v.iter().zip(&should_runs) {
-                    if let Some(suite) = should_run.is_suite_path(path) {
-                        attempted_run = true;
-                        desc.maybe_run(builder, suite);
-                    } else if let Some(pathset) = should_run.pathset_for_path(path) {
-                        attempted_run = true;
-                        desc.maybe_run(builder, pathset);
-                    }
-                }
+        for path in paths {
+            // strip CurDir prefix if present
+            let path = match path.strip_prefix(".") {
+                Ok(p) => p,
+                Err(_) => path,
+            };
 
-                if !attempted_run {
-                    panic!("error: no rules matched {}", path.display());
+            let mut attempted_run = false;
+            for (desc, should_run) in v.iter().zip(&should_runs) {
+                if let Some(suite) = should_run.is_suite_path(path) {
+                    attempted_run = true;
+                    desc.maybe_run(builder, suite);
+                } else if let Some(pathset) = should_run.pathset_for_path(path) {
+                    attempted_run = true;
+                    desc.maybe_run(builder, pathset);
                 }
             }
+
+            if !attempted_run {
+                panic!("error: no rules matched {}", path.display());
+            }
         }
     }
 }
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 6265bbaf5c22c5af508cc71b091ffb6670c64469..db82155bd6ad2172b71b0b3315f78f39a043467d 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -61,6 +61,7 @@ pub struct Config {
     pub profiler: bool,
     pub ignore_git: bool,
     pub exclude: Vec<PathBuf>,
+    pub include_default_paths: bool,
     pub rustc_error_format: Option<String>,
     pub json_output: bool,
     pub test_compare_mode: bool,
@@ -532,6 +533,7 @@ pub fn parse(args: &[String]) -> Config {
 
         let mut config = Config::default_opts();
         config.exclude = flags.exclude;
+        config.include_default_paths = flags.include_default_paths;
         config.rustc_error_format = flags.rustc_error_format;
         config.json_output = flags.json_output;
         config.on_fail = flags.on_fail;
diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index 319a0b4e611ebfedbcdbd8850954f280c6ab852f..c10188875fbc4a46779200a8c48f1190c0d4b1f3 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -30,6 +30,7 @@ pub struct Flags {
     pub cmd: Subcommand,
     pub incremental: bool,
     pub exclude: Vec<PathBuf>,
+    pub include_default_paths: bool,
     pub rustc_error_format: Option<String>,
     pub json_output: bool,
     pub dry_run: bool,
@@ -137,6 +138,11 @@ pub fn parse(args: &[String]) -> Flags {
         opts.optmulti("", "host", "host targets to build", "HOST");
         opts.optmulti("", "target", "target targets to build", "TARGET");
         opts.optmulti("", "exclude", "build paths to exclude", "PATH");
+        opts.optflag(
+            "",
+            "include-default-paths",
+            "include default paths in addition to the provided ones",
+        );
         opts.optopt("", "on-fail", "command to run on failure", "CMD");
         opts.optflag("", "dry-run", "dry run; don't build anything");
         opts.optopt(
@@ -618,6 +624,7 @@ pub fn parse(args: &[String]) -> Flags {
                 .into_iter()
                 .map(|p| p.into())
                 .collect::<Vec<_>>(),
+            include_default_paths: matches.opt_present("include-default-paths"),
             deny_warnings: parse_deny_warnings(&matches),
             llvm_skip_rebuild: matches.opt_str("llvm-skip-rebuild").map(|s| s.to_lowercase()).map(
                 |s| s.parse::<bool>().expect("`llvm-skip-rebuild` should be either true or false"),