Index: lib/Format/FormatToken.h
===================================================================
--- lib/Format/FormatToken.h
+++ lib/Format/FormatToken.h
@@ -53,6 +53,7 @@
   TYPE(JavaAnnotation) \
   TYPE(JsComputedPropertyName) \
   TYPE(JsFatArrow) \
+  TYPE(JsNonNullAssertion) \
   TYPE(JsTypeColon) \
   TYPE(JsTypeOperator) \
   TYPE(JsTypeOptionalQuestion) \
Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -1024,6 +1024,23 @@
       // The token type is already known.
       return;
 
+    if (Style.Language == FormatStyle::LK_JavaScript) {
+      if (Current.is(tok::exclaim)) {
+        if (Current.Previous &&
+            (Current.Previous->isOneOf(tok::identifier, tok::r_paren,
+                                       tok::r_square, tok::r_brace) ||
+             Current.Previous->Tok.isLiteral())) {
+          Current.Type = TT_JsNonNullAssertion;
+          return;
+        }
+        if (Current.Next &&
+            Current.Next->isOneOf(TT_BinaryOperator, Keywords.kw_as)) {
+          Current.Type = TT_JsNonNullAssertion;
+          return;
+        }
+      }
+    }
+
     // Line.MightBeFunctionDecl can only be true after the parentheses of a
     // function declaration have been found. In this case, 'Current' is a
     // trailing token of this declaration and thus cannot be a name.
@@ -2277,12 +2294,9 @@
       // locations that should have whitespace following are identified by the
       // above set of follower tokens.
       return false;
-    // Postfix non-null assertion operator, as in `foo!.bar()`.
-    if (Right.is(tok::exclaim) && (Left.isOneOf(tok::identifier, tok::r_paren,
-                                                tok::r_square, tok::r_brace) ||
-                                   Left.Tok.isLiteral()))
+    if (Right.is(TT_JsNonNullAssertion))
       return false;
-    if (Left.is(tok::exclaim) && Right.is(Keywords.kw_as))
+    if (Left.is(TT_JsNonNullAssertion) && Right.is(Keywords.kw_as))
       return true; // "x! as string"
   } else if (Style.Language == FormatStyle::LK_Java) {
     if (Left.is(tok::r_square) && Right.is(tok::l_brace))
@@ -2535,6 +2549,8 @@
       return false; // must not break before as in 'x as type' casts
     if (Left.is(Keywords.kw_as))
       return true;
+    if (Left.is(TT_JsNonNullAssertion))
+      return true;
     if (Left.is(Keywords.kw_declare) &&
         Right.isOneOf(Keywords.kw_module, tok::kw_namespace,
                       Keywords.kw_function, tok::kw_class, tok::kw_enum,
Index: unittests/Format/FormatTestJS.cpp
===================================================================
--- unittests/Format/FormatTestJS.cpp
+++ unittests/Format/FormatTestJS.cpp
@@ -1679,6 +1679,12 @@
   verifyFormat("let x = (foo)!;\n");
   verifyFormat("let x = foo! - 1;\n");
   verifyFormat("let x = {foo: 1}!;\n");
+  verifyFormat(
+      "let x = hello.foo()!\n"
+      "            .foo()!\n"
+      "            .foo()!\n"
+      "            .foo()!;\n",
+      getGoogleJSStyleWithColumns(20));
 }
 
 TEST_F(FormatTestJS, Conditional) {