diff --git a/src/librustc_interface/passes.rs b/src/librustc_interface/passes.rs
index 5ad737776da..7fcad4d79c2 100644
--- a/src/librustc_interface/passes.rs
+++ b/src/librustc_interface/passes.rs
@@ -230,7 +230,9 @@ pub fn register_plugins<'a>(
     crate_name: &str,
 ) -> Result<(ast::Crate, PluginInfo)> {
     krate = time(sess, "attributes injection", || {
-        syntax::attr::inject(krate, &sess.parse_sess, &sess.opts.debugging_opts.crate_attr)
+        syntax_ext::cmdline_attrs::inject(
+            krate, &sess.parse_sess, &sess.opts.debugging_opts.crate_attr
+        )
     });
 
     let (krate, features) = syntax::config::features(
diff --git a/src/libsyntax/attr/mod.rs b/src/libsyntax/attr/mod.rs
index 0e5cfa73a9e..69de3150354 100644
--- a/src/libsyntax/attr/mod.rs
+++ b/src/libsyntax/attr/mod.rs
@@ -16,7 +16,7 @@
 use crate::source_map::{BytePos, Spanned, DUMMY_SP};
 use crate::parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
 use crate::parse::parser::Parser;
-use crate::parse::{self, ParseSess, PResult};
+use crate::parse::{ParseSess, PResult};
 use crate::parse::token::{self, Token};
 use crate::ptr::P;
 use crate::symbol::{sym, Symbol};
@@ -25,7 +25,7 @@
 use crate::GLOBALS;
 
 use log::debug;
-use syntax_pos::{FileName, Span};
+use syntax_pos::Span;
 
 use std::iter;
 use std::ops::DerefMut;
@@ -381,28 +381,25 @@ pub fn mk_nested_word_item(ident: Ident) -> NestedMetaItem {
     AttrId(id)
 }
 
-/// Returns an inner attribute with the given value and span.
-pub fn mk_attr_inner(item: MetaItem) -> Attribute {
+pub fn mk_attr(style: AttrStyle, path: Path, tokens: TokenStream, span: Span) -> Attribute {
     Attribute {
         id: mk_attr_id(),
-        style: ast::AttrStyle::Inner,
-        path: item.path,
-        tokens: item.node.tokens(item.span),
+        style,
+        path,
+        tokens,
         is_sugared_doc: false,
-        span: item.span,
+        span,
     }
 }
 
+/// Returns an inner attribute with the given value and span.
+pub fn mk_attr_inner(item: MetaItem) -> Attribute {
+    mk_attr(AttrStyle::Inner, item.path, item.node.tokens(item.span), item.span)
+}
+
 /// Returns an outer attribute with the given value and span.
 pub fn mk_attr_outer(item: MetaItem) -> Attribute {
-    Attribute {
-        id: mk_attr_id(),
-        style: ast::AttrStyle::Outer,
-        path: item.path,
-        tokens: item.node.tokens(item.span),
-        is_sugared_doc: false,
-        span: item.span,
-    }
+    mk_attr(AttrStyle::Outer, item.path, item.node.tokens(item.span), item.span)
 }
 
 pub fn mk_sugared_doc_attr(text: Symbol, span: Span) -> Attribute {
@@ -716,33 +713,3 @@ fn visit_attrs<F: FnOnce(&mut Vec<Attribute>)>(&mut self, f: F) {
     Item, Expr, Local, ast::ForeignItem, ast::StructField, ast::ImplItem, ast::TraitItem, ast::Arm,
     ast::Field, ast::FieldPat, ast::Variant, ast::Param
 }
-
-pub fn inject(mut krate: ast::Crate, parse_sess: &ParseSess, attrs: &[String]) -> ast::Crate {
-    for raw_attr in attrs {
-        let mut parser = parse::new_parser_from_source_str(
-            parse_sess,
-            FileName::cli_crate_attr_source_code(&raw_attr),
-            raw_attr.clone(),
-        );
-
-        let start_span = parser.token.span;
-        let (path, tokens) = panictry!(parser.parse_meta_item_unrestricted());
-        let end_span = parser.token.span;
-        if parser.token != token::Eof {
-            parse_sess.span_diagnostic
-                .span_err(start_span.to(end_span), "invalid crate attribute");
-            continue;
-        }
-
-        krate.attrs.push(Attribute {
-            id: mk_attr_id(),
-            style: AttrStyle::Inner,
-            path,
-            tokens,
-            is_sugared_doc: false,
-            span: start_span.to(end_span),
-        });
-    }
-
-    krate
-}
diff --git a/src/libsyntax/parse/attr.rs b/src/libsyntax/parse/attr.rs
index 671178223f5..d9c4baad49d 100644
--- a/src/libsyntax/parse/attr.rs
+++ b/src/libsyntax/parse/attr.rs
@@ -176,7 +176,7 @@ fn parse_attribute_with_inner_parse_policy(&mut self,
     /// PATH
     /// PATH `=` TOKEN_TREE
     /// The delimiters or `=` are still put into the resulting token stream.
-    crate fn parse_meta_item_unrestricted(&mut self) -> PResult<'a, (ast::Path, TokenStream)> {
+    pub fn parse_meta_item_unrestricted(&mut self) -> PResult<'a, (ast::Path, TokenStream)> {
         let meta = match self.token.kind {
             token::Interpolated(ref nt) => match **nt {
                 Nonterminal::NtMeta(ref meta) => Some(meta.clone()),
diff --git a/src/libsyntax_ext/cmdline_attrs.rs b/src/libsyntax_ext/cmdline_attrs.rs
new file mode 100644
index 00000000000..bb8e3df3db9
--- /dev/null
+++ b/src/libsyntax_ext/cmdline_attrs.rs
@@ -0,0 +1,30 @@
+//! Attributes injected into the crate root from command line using `-Z crate-attr`.
+
+use syntax::ast::{self, AttrStyle};
+use syntax::attr::mk_attr;
+use syntax::panictry;
+use syntax::parse::{self, token, ParseSess};
+use syntax_pos::FileName;
+
+pub fn inject(mut krate: ast::Crate, parse_sess: &ParseSess, attrs: &[String]) -> ast::Crate {
+    for raw_attr in attrs {
+        let mut parser = parse::new_parser_from_source_str(
+            parse_sess,
+            FileName::cli_crate_attr_source_code(&raw_attr),
+            raw_attr.clone(),
+        );
+
+        let start_span = parser.token.span;
+        let (path, tokens) = panictry!(parser.parse_meta_item_unrestricted());
+        let end_span = parser.token.span;
+        if parser.token != token::Eof {
+            parse_sess.span_diagnostic
+                .span_err(start_span.to(end_span), "invalid crate attribute");
+            continue;
+        }
+
+        krate.attrs.push(mk_attr(AttrStyle::Inner, path, tokens, start_span.to(end_span)));
+    }
+
+    krate
+}
diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index 26ef80b2b06..5c0a63ebbe7 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -40,6 +40,7 @@
 mod test;
 mod trace_macros;
 
+pub mod cmdline_attrs;
 pub mod plugin_macro_defs;
 pub mod proc_macro_harness;
 pub mod standard_library_imports;