diff --git a/src/doc/book b/src/doc/book
index e79dd62aa6339..28fa3d15b0bc6 160000
--- a/src/doc/book
+++ b/src/doc/book
@@ -1 +1 @@
-Subproject commit e79dd62aa63396714278d484d91d48826737f47f
+Subproject commit 28fa3d15b0bc67ea5e79eeff2198e4277fc61baf
diff --git a/src/doc/edition-guide b/src/doc/edition-guide
index f553fb26c60c4..e58bc4ca104e8 160000
--- a/src/doc/edition-guide
+++ b/src/doc/edition-guide
@@ -1 +1 @@
-Subproject commit f553fb26c60c4623ea88a1cfe731eafe0643ce34
+Subproject commit e58bc4ca104e890ac56af846877c874c432a64b5
diff --git a/src/doc/nomicon b/src/doc/nomicon
index 58e36e0e08dec..5004ad30d69f9 160000
--- a/src/doc/nomicon
+++ b/src/doc/nomicon
@@ -1 +1 @@
-Subproject commit 58e36e0e08dec5a379ac568827c058e25990d6cd
+Subproject commit 5004ad30d69f93553ceef74439fea2159d1f769e
diff --git a/src/doc/reference b/src/doc/reference
index 45558c464fb45..4b21b646669e0 160000
--- a/src/doc/reference
+++ b/src/doc/reference
@@ -1 +1 @@
-Subproject commit 45558c464fb458affbcdcb34323946da45c8a117
+Subproject commit 4b21b646669e0af49fae7cae301898dc4bfaa1f0
diff --git a/src/doc/rust-by-example b/src/doc/rust-by-example
index dcee312c66267..f3197ddf2abab 160000
--- a/src/doc/rust-by-example
+++ b/src/doc/rust-by-example
@@ -1 +1 @@
-Subproject commit dcee312c66267eb5a2f6f1561354003950e29105
+Subproject commit f3197ddf2abab9abdbc029def8164f4a748b0d91
diff --git a/src/doc/rustc-guide b/src/doc/rustc-guide
index 934380b7cfcea..941968db2fd9c 160000
--- a/src/doc/rustc-guide
+++ b/src/doc/rustc-guide
@@ -1 +1 @@
-Subproject commit 934380b7cfceaaa4e1b9bb0de4a372f32725520b
+Subproject commit 941968db2fd9c85788a4f971c8e425d46b4cb734
diff --git a/src/liballoc/string.rs b/src/liballoc/string.rs
index f7dff4c21f7c4..f806e5ca31f46 100644
--- a/src/liballoc/string.rs
+++ b/src/liballoc/string.rs
@@ -1982,6 +1982,91 @@ impl Add<&str> for String {
     }
 }
 
+// This had to be added to avoid breakage after adding `impl Add<char> for String`
+#[allow(missing_docs)]
+#[stable(feature = "extra_add_string_and_dbl_ref_str", since = "1.41.0")]
+impl Add<&&str> for String {
+    type Output = String;
+
+    #[inline]
+    fn add(mut self, other: &&str) -> String {
+        self.push_str(other);
+        self
+    }
+}
+
+// This had to be added to avoid breakage after adding `impl Add<char> for String`
+#[allow(missing_docs)]
+#[stable(feature = "extra_add_string_and_ref_string", since = "1.41.0")]
+impl Add<&String> for String {
+    type Output = String;
+
+    #[inline]
+    fn add(mut self, other: &String) -> String {
+        self.push_str(other);
+        self
+    }
+}
+
+// This had to be added to avoid breakage after adding `impl Add<char> for String`
+#[allow(missing_docs)]
+#[stable(feature = "extra_add_string_and_dbl_ref_string", since = "1.41.0")]
+impl Add<&&String> for String {
+    type Output = String;
+
+    #[inline]
+    fn add(mut self, other: &&String) -> String {
+        self.push_str(other);
+        self
+    }
+}
+
+/// Implements the `+` operator for concatenating a string and a char together.
+///
+/// This consumes the `String` on the left-hand side and re-uses its buffer (growing it if
+/// necessary). This is done to avoid allocating a new `String` and copying the entire contents on
+/// every operation, which would lead to `O(n^2)` running time when building an `n`-byte string by
+/// repeated concatenation.
+///
+/// # Examples
+///
+/// Concatenating a `String` with a `char` takes the `String` by value and copies the `char`:
+///
+/// ```
+/// let a = String::from("hello world! ");
+/// let b = '👋';
+/// let c = a + b;
+/// // `a` is moved and can no longer be used here.
+/// ```
+///
+/// If you want to keep using the initial `String`, you can clone it and append to the
+/// clone instead:
+///
+/// ```
+/// let a = String::from("hello world! ");
+/// let b = '👋';
+/// let c = a.clone() + b;
+/// // `a` is still valid here.
+/// ```
+///
+/// Concatenating `char` to a `&str` slice can be done by converting the `&str` to a `String`:
+///
+/// ```
+/// let a = "hello world! ";
+/// let b = '👋';
+/// let c = a.to_string() + b;
+/// ```
+#[stable(feature = "add_string_and_char", since = "1.41.0")]
+impl Add<char> for String {
+    type Output = String;
+
+    #[inline]
+    fn add(mut self, other: char) -> String {
+        self.push(other);
+        self
+    }
+}
+
 /// Implements the `+=` operator for appending to a `String`.
 ///
 /// This has the same behavior as the [`push_str`][String::push_str] method.
@@ -1993,6 +2078,28 @@ impl AddAssign<&str> for String {
     }
 }
 
+/// Implements the `+=` operator for appending to a `String`.
+///
+/// This has the same behavior as the [`push_str`][String::push_str] method.
+#[stable(feature = "string_add_assign_string", since = "1.41.0")]
+impl AddAssign<&String> for String {
+    #[inline]
+    fn add_assign(&mut self, other: &String) {
+        self.push_str(other);
+    }
+}
+
+/// Implements the `+=` operator for appending a `char` to a `String`.
+///
+/// This has the same behavior as the [`push`][String::push] method.
+#[stable(feature = "string_add_assign_char", since = "1.41.0")]
+impl AddAssign<char> for String {
+    #[inline]
+    fn add_assign(&mut self, other: char) {
+        self.push(other);
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Index<ops::Range<usize>> for String {
     type Output = str;
diff --git a/src/liballoc/tests/string.rs b/src/liballoc/tests/string.rs
index 55edf56345b59..81f66d9e67f49 100644
--- a/src/liballoc/tests/string.rs
+++ b/src/liballoc/tests/string.rs
@@ -195,8 +195,10 @@ fn test_add_assign() {
     assert_eq!(s.as_str(), "");
     s += "abc";
     assert_eq!(s.as_str(), "abc");
-    s += "ประเทศไทย中华Việt Nam";
-    assert_eq!(s.as_str(), "abcประเทศไทย中华Việt Nam");
+    s += "ประเทศไทย中华Việt Nam ";
+    assert_eq!(s.as_str(), "abcประเทศไทย中华Việt Nam ");
+    s += '👋';
+    assert_eq!(s.as_str(), "abcประเทศไทย中华Việt Nam 👋")
 }
 
 #[test]
@@ -304,9 +306,10 @@ fn test_str_clear() {
 fn test_str_add() {
     let a = String::from("12345");
     let b = a + "2";
-    let b = b + "2";
-    assert_eq!(b.len(), 7);
-    assert_eq!(b, "1234522");
+    let b = b + "2 ";
+    let b = b + '👋';
+    assert_eq!(b.len(), 12);
+    assert_eq!(b, "1234522 👋");
 }
 
 #[test]
diff --git a/src/librustc_parse/parser/expr.rs b/src/librustc_parse/parser/expr.rs
index a56a7bf1802c7..1f0f3f2020117 100644
--- a/src/librustc_parse/parser/expr.rs
+++ b/src/librustc_parse/parser/expr.rs
@@ -1110,7 +1110,7 @@ impl<'a> Parser<'a> {
                 if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix })
                         = next_token.kind {
                     if self.token.span.hi() == next_token.span.lo() {
-                        let s = String::from("0.") + &symbol.as_str();
+                        let s = String::from("0.") + &*symbol.as_str();
                         let kind = TokenKind::lit(token::Float, Symbol::intern(&s), suffix);
                         return Some(Token::new(kind, self.token.span.to(next_token.span)));
                     }
diff --git a/src/llvm-project b/src/llvm-project
index cf9304d6d0c6a..14a3b123074e0 160000
--- a/src/llvm-project
+++ b/src/llvm-project
@@ -1 +1 @@
-Subproject commit cf9304d6d0c6a66c27a1664dd55d8bcc8be0bf09
+Subproject commit 14a3b123074e066d64a99886941473058e52197d
diff --git a/src/tools/cargo b/src/tools/cargo
index 8280633db680d..5da4b4d479638 160000
--- a/src/tools/cargo
+++ b/src/tools/cargo
@@ -1 +1 @@
-Subproject commit 8280633db680dec5bfe1de25156d1a1d53e6d190
+Subproject commit 5da4b4d47963868d9878480197581ccbbdaece74
diff --git a/src/tools/clippy b/src/tools/clippy
index b4f1769734b62..c8e3cfbdd9978 160000
--- a/src/tools/clippy
+++ b/src/tools/clippy
@@ -1 +1 @@
-Subproject commit b4f1769734b6204fc6bece8556b7b80a7683271e
+Subproject commit c8e3cfbdd997839c771ca32c7ac860fe95149a04
diff --git a/src/tools/miri b/src/tools/miri
index 67a63f89d8c0e..d4e4fe71e6a95 160000
--- a/src/tools/miri
+++ b/src/tools/miri
@@ -1 +1 @@
-Subproject commit 67a63f89d8c0e5b22fb52cc33274283819f41792
+Subproject commit d4e4fe71e6a9568f5d081d99f1c621c5a4ddd7db