diff --git a/src/librustc/hir/print.rs b/src/librustc/hir/print.rs
index 3af72dbb43c..fc3430566a0 100644
--- a/src/librustc/hir/print.rs
+++ b/src/librustc/hir/print.rs
@@ -16,7 +16,6 @@ use crate::hir::ptr::P;
 
 use std::borrow::Cow;
 use std::cell::Cell;
-use std::io::Read;
 use std::vec;
 
 pub enum AnnNode<'a> {
@@ -93,7 +92,7 @@ pub fn print_crate<'a>(cm: &'a SourceMap,
                        sess: &ParseSess,
                        krate: &hir::Crate,
                        filename: FileName,
-                       input: &mut dyn Read,
+                       input: String,
                        out: &'a mut String,
                        ann: &'a dyn PpAnn)
                        {
@@ -111,7 +110,7 @@ impl<'a> State<'a> {
     pub fn new_from_input(cm: &'a SourceMap,
                           sess: &ParseSess,
                           filename: FileName,
-                          input: &mut dyn Read,
+                          input: String,
                           out: &'a mut String,
                           ann: &'a dyn PpAnn)
                           -> State<'a> {
diff --git a/src/librustc_driver/pretty.rs b/src/librustc_driver/pretty.rs
index fc55d5ac355..df8dc3871b7 100644
--- a/src/librustc_driver/pretty.rs
+++ b/src/librustc_driver/pretty.rs
@@ -687,16 +687,14 @@ pub fn visit_crate(sess: &Session, krate: &mut ast::Crate, ppm: PpMode) {
     }
 }
 
-fn get_source(input: &Input, sess: &Session) -> (Vec<u8>, FileName) {
+fn get_source(input: &Input, sess: &Session) -> (String, FileName) {
     let src_name = source_name(input);
-    let src = sess.source_map()
+    let src = String::clone(&sess.source_map()
         .get_source_file(&src_name)
         .unwrap()
         .src
         .as_ref()
-        .unwrap()
-        .as_bytes()
-        .to_vec();
+        .unwrap());
     (src, src_name)
 }
 
@@ -719,7 +717,6 @@ pub fn print_after_parsing(sess: &Session,
                            ofile: Option<&Path>) {
     let (src, src_name) = get_source(input, sess);
 
-    let mut rdr = &*src;
     let mut out = String::new();
 
     if let PpmSource(s) = ppm {
@@ -732,7 +729,7 @@ pub fn print_after_parsing(sess: &Session,
                                 &sess.parse_sess,
                                 krate,
                                 src_name,
-                                &mut rdr,
+                                src,
                                 out,
                                 annotation.pp_ann(),
                                 false)
@@ -764,13 +761,13 @@ pub fn print_after_hir_lowering<'tcx>(
 
     let (src, src_name) = get_source(input, tcx.sess);
 
-    let mut rdr = &src[..];
     let mut out = String::new();
 
     match (ppm, opt_uii) {
             (PpmSource(s), _) => {
                 // Silently ignores an identified node.
                 let out = &mut out;
+                let src = src.clone();
                 s.call_with_pp_support(tcx.sess, Some(tcx), move |annotation| {
                     debug!("pretty printing source code {:?}", s);
                     let sess = annotation.sess();
@@ -778,7 +775,7 @@ pub fn print_after_hir_lowering<'tcx>(
                                         &sess.parse_sess,
                                         krate,
                                         src_name,
-                                        &mut rdr,
+                                        src,
                                         out,
                                         annotation.pp_ann(),
                                         true)
@@ -787,6 +784,7 @@ pub fn print_after_hir_lowering<'tcx>(
 
             (PpmHir(s), None) => {
                 let out = &mut out;
+                let src = src.clone();
                 s.call_with_pp_support_hir(tcx, move |annotation, krate| {
                     debug!("pretty printing source code {:?}", s);
                     let sess = annotation.sess();
@@ -794,7 +792,7 @@ pub fn print_after_hir_lowering<'tcx>(
                                             &sess.parse_sess,
                                             krate,
                                             src_name,
-                                            &mut rdr,
+                                            src,
                                             out,
                                             annotation.pp_ann())
                 })
@@ -810,6 +808,7 @@ pub fn print_after_hir_lowering<'tcx>(
 
             (PpmHir(s), Some(uii)) => {
                 let out = &mut out;
+                let src = src.clone();
                 s.call_with_pp_support_hir(tcx, move |annotation, _| {
                     debug!("pretty printing source code {:?}", s);
                     let sess = annotation.sess();
@@ -817,7 +816,7 @@ pub fn print_after_hir_lowering<'tcx>(
                     let mut pp_state = pprust_hir::State::new_from_input(sess.source_map(),
                                                                          &sess.parse_sess,
                                                                          src_name,
-                                                                         &mut rdr,
+                                                                         src,
                                                                          out,
                                                                          annotation.pp_ann());
                     for node_id in uii.all_matching_node_ids(hir_map) {
diff --git a/src/libsyntax/parse/lexer/comments.rs b/src/libsyntax/parse/lexer/comments.rs
index 988f1aa38d9..6ed2a7adad1 100644
--- a/src/libsyntax/parse/lexer/comments.rs
+++ b/src/libsyntax/parse/lexer/comments.rs
@@ -8,7 +8,6 @@ use crate::parse::lexer::{self, ParseSess, StringReader};
 use syntax_pos::{BytePos, CharPos, Pos, FileName};
 use log::debug;
 
-use std::io::Read;
 use std::usize;
 
 #[derive(Clone, Copy, PartialEq, Debug)]
@@ -340,10 +339,8 @@ fn consume_comment(rdr: &mut StringReader<'_>,
 
 // it appears this function is called only from pprust... that's
 // probably not a good thing.
-pub fn gather_comments(sess: &ParseSess, path: FileName, srdr: &mut dyn Read) -> Vec<Comment>
+pub fn gather_comments(sess: &ParseSess, path: FileName, src: String) -> Vec<Comment>
 {
-    let mut src = String::new();
-    srdr.read_to_string(&mut src).unwrap();
     let cm = SourceMap::new(sess.source_map().path_mapping().clone());
     let source_file = cm.new_source_file(path, src);
     let mut rdr = lexer::StringReader::new(sess, source_file, None);
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 638384acc4c..a6680ee02b5 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -21,7 +21,6 @@ use syntax_pos::{self, BytePos};
 use syntax_pos::{DUMMY_SP, FileName, Span};
 
 use std::borrow::Cow;
-use std::io::Read;
 
 pub enum AnnNode<'a> {
     Ident(&'a ast::Ident),
@@ -102,7 +101,7 @@ pub fn print_crate<'a>(cm: &'a SourceMap,
                        sess: &ParseSess,
                        krate: &ast::Crate,
                        filename: FileName,
-                       input: &mut dyn Read,
+                       input: String,
                        out: &mut String,
                        ann: &'a dyn PpAnn,
                        is_expanded: bool) {
@@ -136,7 +135,7 @@ impl<'a> State<'a> {
     pub fn new_from_input(cm: &'a SourceMap,
                           sess: &ParseSess,
                           filename: FileName,
-                          input: &mut dyn Read,
+                          input: String,
                           out: &'a mut String,
                           ann: &'a dyn PpAnn,
                           is_expanded: bool) -> State<'a> {