diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -2746,6 +2746,10 @@
                        tok::kw_void))
         return true;
     }
+    // `foo as const;` casts into a const type.
+    if (Left.endsSequence(tok::kw_const, Keywords.kw_as)) {
+      return false;
+    }
     if ((Left.isOneOf(Keywords.kw_let, Keywords.kw_var, Keywords.kw_in,
                       tok::kw_const) ||
          // "of" is only a keyword if it appears after another identifier
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -1479,6 +1479,9 @@
       "                    .someFunction(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa);");
   verifyFormat("const xIsALongIdent:\n""    YJustBarelyFitsLinex[];",
       getGoogleJSStyleWithColumns(20));
+  verifyFormat("const x = {\n"
+               "  y: 1\n"
+               "} as const;");
 }
 
 TEST_F(FormatTestJS, UnionIntersectionTypes) {