diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index b469cfad2bbc..13bda71127ff 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -2126,6 +2126,11 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
       // 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()))
+      return false;
   } else if (Style.Language == FormatStyle::LK_Java) {
     if (Left.is(tok::r_square) && Right.is(tok::l_brace))
       return true;
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index 3d9677922cff..ffcc34d971f6 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -1293,5 +1293,14 @@ TEST_F(FormatTestJS, SupportShebangLines) {
                "var x   =  hello();");
 }
 
+TEST_F(FormatTestJS, NonNullAssertionOperator) {
+  verifyFormat("let x = foo!.bar();\n");
+  verifyFormat("let x = foo ? bar! : baz;\n");
+  verifyFormat("let x = !foo;\n");
+  verifyFormat("let x = foo[0]!;\n");
+  verifyFormat("let x = (foo)!;\n");
+  verifyFormat("let x = {foo: 1}!;\n");
+}
+
 } // end namespace tooling
 } // end namespace clang