diff --git a/clang/lib/Format/FormatToken.h b/clang/lib/Format/FormatToken.h
--- a/clang/lib/Format/FormatToken.h
+++ b/clang/lib/Format/FormatToken.h
@@ -96,6 +96,7 @@
   TYPE(PointerOrReference)                                                     \
   TYPE(PureVirtualSpecifier)                                                   \
   TYPE(RangeBasedForLoopColon)                                                 \
+  TYPE(RecordLBrace)                                                           \
   TYPE(RegexLiteral)                                                           \
   TYPE(SelectorName)                                                           \
   TYPE(StartOfName)                                                            \
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
@@ -1423,7 +1423,8 @@
             TT_LambdaArrow, TT_NamespaceMacro, TT_OverloadedOperator,
             TT_RegexLiteral, TT_TemplateString, TT_ObjCStringLiteral,
             TT_UntouchableMacroFunc, TT_ConstraintJunctions,
-            TT_StatementAttributeLikeMacro, TT_FunctionLikeOrFreestandingMacro))
+            TT_StatementAttributeLikeMacro, TT_FunctionLikeOrFreestandingMacro,
+            TT_RecordLBrace))
       CurrentToken->setType(TT_Unknown);
     CurrentToken->Role.reset();
     CurrentToken->MatchingParen = nullptr;
diff --git a/clang/lib/Format/UnwrappedLineFormatter.cpp b/clang/lib/Format/UnwrappedLineFormatter.cpp
--- a/clang/lib/Format/UnwrappedLineFormatter.cpp
+++ b/clang/lib/Format/UnwrappedLineFormatter.cpp
@@ -276,6 +276,9 @@
               FormatStyle::SFS_InlineOnly) {
             // Just checking TheLine->Level != 0 is not enough, because it
             // provokes treating functions inside indented namespaces as short.
+            if (Style.isJavaScript() && (*I)->Last->is(TT_FunctionLBrace))
+              return true;
+
             if ((*I)->Level != 0) {
               if (I == B)
                 return false;
@@ -288,23 +291,10 @@
                   break;
 
               // Check if the found line starts a record.
-              auto *RecordTok = (*J)->First;
-              while (RecordTok) {
-                // TODO: Refactor to isRecord(RecordTok).
-                if (RecordTok->isOneOf(tok::kw_class, tok::kw_struct))
-                  return true;
-                if (Style.isCpp() && RecordTok->is(tok::kw_union))
-                  return true;
-                if (Style.isCSharp() && RecordTok->is(Keywords.kw_interface))
-                  return true;
-                if (Style.Language == FormatStyle::LK_Java &&
-                    RecordTok->is(tok::kw_enum))
-                  return true;
-                if (Style.isJavaScript() && RecordTok->is(Keywords.kw_function))
-                  return true;
-
-                RecordTok = RecordTok->Next;
-              }
+              for (const FormatToken *RecordTok = (*J)->Last; RecordTok;
+                   RecordTok = RecordTok->Previous)
+                if (RecordTok->is(tok::l_brace))
+                  return RecordTok->is(TT_RecordLBrace);
 
               return false;
             }
diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -2482,7 +2482,8 @@
     parseParens();
   } else {
     while (FormatTok->isOneOf(tok::identifier, tok::coloncolon, tok::kw_inline,
-                              tok::l_square, tok::period)) {
+                              tok::l_square, tok::period) ||
+           (Style.isCSharp() && FormatTok->is(tok::kw_union))) {
       if (FormatTok->is(tok::l_square))
         parseSquare();
       else
@@ -2868,6 +2869,7 @@
   // Just a declaration or something is wrong.
   if (FormatTok->isNot(tok::l_brace))
     return true;
+  FormatTok->setType(TT_RecordLBrace);
   FormatTok->setBlockKind(BK_Block);
 
   if (Style.Language == FormatStyle::LK_Java) {
@@ -3108,6 +3110,7 @@
     }
   }
   if (FormatTok->Tok.is(tok::l_brace)) {
+    FormatTok->setType(TT_RecordLBrace);
     if (ParseAsExpr) {
       parseChildBlock();
     } else {
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -12316,6 +12316,48 @@
                "  int f() {}\n"
                "};",
                MergeInlineOnly);
+
+  MergeInlineOnly.BraceWrapping.AfterClass = true;
+  MergeInlineOnly.BraceWrapping.AfterStruct = true;
+  verifyFormat("class C\n"
+               "{\n"
+               "  int f() { return 42; }\n"
+               "};",
+               MergeInlineOnly);
+  verifyFormat("struct C\n"
+               "{\n"
+               "  int f() { return 42; }\n"
+               "};",
+               MergeInlineOnly);
+  verifyFormat("int f()\n"
+               "{\n"
+               "  return 42;\n"
+               "}",
+               MergeInlineOnly);
+  verifyFormat("int f() {}", MergeInlineOnly);
+  verifyFormat("class C\n"
+               "{\n"
+               "  int f() { return 42; }\n"
+               "};",
+               MergeInlineOnly);
+  verifyFormat("struct C\n"
+               "{\n"
+               "  int f() { return 42; }\n"
+               "};",
+               MergeInlineOnly);
+  verifyFormat("struct C\n"
+               "// comment\n"
+               "/* comment */\n"
+               "// comment\n"
+               "{\n"
+               "  int f() { return 42; }\n"
+               "};",
+               MergeInlineOnly);
+  verifyFormat("/* comment */ struct C\n"
+               "{\n"
+               "  int f() { return 42; }\n"
+               "};",
+               MergeInlineOnly);
 }
 
 TEST_F(FormatTest, PullInlineOnlyFunctionDefinitionsIntoSingleLine) {
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -67,6 +67,30 @@
   EXPECT_TOKEN(Tokens[11], tok::star, TT_PointerOrReference);
 }
 
+TEST_F(TokenAnnotatorTest, UnderstandsClasses) {
+  auto Tokens = annotate("class C {};");
+  EXPECT_EQ(Tokens.size(), 6u) << Tokens;
+  EXPECT_TOKEN(Tokens[2], tok::l_brace, TT_RecordLBrace);
+}
+
+TEST_F(TokenAnnotatorTest, UnderstandsStructs) {
+  auto Tokens = annotate("struct S {};");
+  EXPECT_EQ(Tokens.size(), 6u) << Tokens;
+  EXPECT_TOKEN(Tokens[2], tok::l_brace, TT_RecordLBrace);
+}
+
+TEST_F(TokenAnnotatorTest, UnderstandsUnions) {
+  auto Tokens = annotate("union U {};");
+  EXPECT_EQ(Tokens.size(), 6u) << Tokens;
+  EXPECT_TOKEN(Tokens[2], tok::l_brace, TT_RecordLBrace);
+}
+
+TEST_F(TokenAnnotatorTest, UnderstandsEnums) {
+  auto Tokens = annotate("enum E {};");
+  EXPECT_EQ(Tokens.size(), 6u) << Tokens;
+  EXPECT_TOKEN(Tokens[2], tok::l_brace, TT_RecordLBrace);
+}
+
 } // namespace
 } // namespace format
 } // namespace clang