diff --git a/src/common.rs b/src/common.rs
index 17eaa54..332e9a6 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -229,6 +229,11 @@ pub struct Config {
     /// The default Rust edition
     pub edition: Option<String>,
 
+    /// Whether parsing of headers uses `//@` and errors on malformed headers or
+    /// just allows any comment to have headers and silently ignores things that don't parse
+    /// as a header.
+    pub strict_headers: bool,
+
     // Configuration for various run-make tests frobbing things like C compilers
     // or querying about various LLVM component information.
     pub cc: String,
@@ -420,6 +425,7 @@ impl Default for Config {
             llvm_cxxflags: "llvm-cxxflags".to_string(),
             nodejs: None,
             edition: None,
+            strict_headers: false,
         }
     }
 }
diff --git a/src/header.rs b/src/header.rs
index 6aea9bb..9652b18 100644
--- a/src/header.rs
+++ b/src/header.rs
@@ -38,6 +38,7 @@ impl EarlyProps {
 
         iter_header(testfile,
                     None,
+                    config,
                     &mut |ln| {
             props.ignore =
                 props.ignore ||
@@ -300,6 +301,7 @@ impl TestProps {
         let mut has_edition = false;
         iter_header(testfile,
                     cfg,
+                    config,
                     &mut |ln| {
             if let Some(ep) = config.parse_error_pattern(ln) {
                 self.error_patterns.push(ep);
@@ -422,10 +424,16 @@ impl TestProps {
     }
 }
 
-fn iter_header(testfile: &Path, cfg: Option<&str>, it: &mut dyn FnMut(&str)) {
+const HEADER_PREFIXES: [[&str; 2]; 2] = [
+    ["//", "//["],
+    ["//@", "//@["],
+];
+
+fn iter_header(testfile: &Path, cfg: Option<&str>, config: &Config, it: &mut dyn FnMut(&str)) {
     if testfile.is_dir() {
         return;
     }
+    let header_prefix = HEADER_PREFIXES[config.strict_headers as usize];
     let rdr = BufReader::new(File::open(testfile).unwrap());
     for ln in rdr.lines() {
         // Assume that any directives will be found before the first
@@ -435,7 +443,7 @@ fn iter_header(testfile: &Path, cfg: Option<&str>, it: &mut dyn FnMut(&str)) {
         let ln = ln.trim();
         if ln.starts_with("fn") || ln.starts_with("mod") {
             return;
-        } else if let Some(ln) = ln.strip_prefix("//@[") {
+        } else if let Some(ln) = ln.strip_prefix(header_prefix[1]) {
             // A comment like `//[foo]` is specific to revision `foo`
             if let Some((lncfg, ln)) = ln.split_once(']') {
                 if cfg == Some(lncfg) {
@@ -447,7 +455,7 @@ fn iter_header(testfile: &Path, cfg: Option<&str>, it: &mut dyn FnMut(&str)) {
                     ln
                 )
             }
-        } else if let Some(ln) = ln.strip_prefix("//@") {
+        } else if let Some(ln) = ln.strip_prefix(header_prefix[0]) {
             it(ln.trim_start());
         }
     }
diff --git a/test-project/tests/tests.rs b/test-project/tests/tests.rs
index c46710c..52466dc 100644
--- a/test-project/tests/tests.rs
+++ b/test-project/tests/tests.rs
@@ -18,6 +18,7 @@ fn run_mode(mode: &'static str, custom_dir: Option<&'static str>) {
             .into(),
     );
     config.clean_rmeta();
+    config.strict_headers = true;
 
     compiletest::run_tests(&config);
 }