Index: clang/docs/ClangFormatStyleOptions.rst
===================================================================
--- clang/docs/ClangFormatStyleOptions.rst
+++ clang/docs/ClangFormatStyleOptions.rst
@@ -537,6 +537,11 @@
   If ``true``, ``while (true) continue;`` can be put on a single
   line.
 
+**AllowShortEnumsOnASingleLine** (``bool``)
+  Allows contracting enums to a single line.
+
+  E.g., this allows ``enum {A, B, C};`` to be put on a single line.
+
 **AlwaysBreakAfterDefinitionReturnType** (``DefinitionReturnTypeBreakingStyle``)
   The function definition return type breaking style to use.  This
   option is **deprecated** and is retained for backwards compatibility.
Index: clang/include/clang/Format/Format.h
===================================================================
--- clang/include/clang/Format/Format.h
+++ clang/include/clang/Format/Format.h
@@ -383,6 +383,9 @@
   /// line.
   bool AllowShortLoopsOnASingleLine;
 
+  /// If ``true``, ``enum {A, B, C};`` can be put on a single line.
+  bool AllowShortEnumsOnASingleLine;
+
   /// Different ways to break after the function definition return type.
   /// This option is **deprecated** and is retained for backwards compatibility.
   enum DefinitionReturnTypeBreakingStyle {
Index: clang/lib/Format/Format.cpp
===================================================================
--- clang/lib/Format/Format.cpp
+++ clang/lib/Format/Format.cpp
@@ -401,6 +401,8 @@
                    Style.AllowShortIfStatementsOnASingleLine);
     IO.mapOptional("AllowShortLoopsOnASingleLine",
                    Style.AllowShortLoopsOnASingleLine);
+    IO.mapOptional("AllowShortEnumsOnASingleLine",
+                   Style.AllowShortEnumsOnASingleLine);
     IO.mapOptional("AlwaysBreakAfterDefinitionReturnType",
                    Style.AlwaysBreakAfterDefinitionReturnType);
     IO.mapOptional("AlwaysBreakAfterReturnType",
@@ -734,6 +736,7 @@
   LLVMStyle.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
   LLVMStyle.AllowShortLambdasOnASingleLine = FormatStyle::SLS_All;
   LLVMStyle.AllowShortLoopsOnASingleLine = false;
+  LLVMStyle.AllowShortEnumsOnASingleLine = true;
   LLVMStyle.AlwaysBreakAfterReturnType = FormatStyle::RTBS_None;
   LLVMStyle.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_None;
   LLVMStyle.AlwaysBreakBeforeMultilineStrings = false;
Index: clang/lib/Format/TokenAnnotator.cpp
===================================================================
--- clang/lib/Format/TokenAnnotator.cpp
+++ clang/lib/Format/TokenAnnotator.cpp
@@ -3106,6 +3106,10 @@
   }
   if (Right.is(TT_InlineASMBrace))
     return Right.HasUnescapedNewline;
+  if (isAllmanBrace(Left) && !Style.AllowShortEnumsOnASingleLine &&
+      (Line.startsWith(tok::kw_enum) ||
+       Line.startsWith(tok::kw_typedef, tok::kw_enum)))
+    return true;
   if (isAllmanBrace(Left) || isAllmanBrace(Right))
     return (Line.startsWith(tok::kw_enum) && Style.BraceWrapping.AfterEnum) ||
            (Line.startsWith(tok::kw_typedef, tok::kw_enum) &&
Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -1798,6 +1798,24 @@
   verifyFormat("enum ShortEnum { A, B, C };");
   verifyGoogleFormat("enum ShortEnum { A, B, C };");
 
+  FormatStyle Style = getLLVMStyle();
+  Style.AllowShortEnumsOnASingleLine = false;
+  verifyFormat("enum Enum {\n"
+               "};",Style);
+  verifyFormat("enum {\n"
+               "};",Style);
+  verifyFormat("enum X E {\n"
+               "} d;",Style);
+  verifyFormat("enum __attribute__((...)) E {\n"
+               "} d;",Style);
+  verifyFormat("enum __declspec__((...)) E {\n"
+               "} d;",Style);
+  verifyFormat("enum ShortEnum {\n"
+               "  A,\n"
+               "  B,\n"
+               "  C\n"
+               "};",Style);
+
   EXPECT_EQ("enum KeepEmptyLines {\n"
             "  ONE,\n"
             "\n"
@@ -1866,6 +1884,19 @@
   verifyFormat("enum struct __attribute__((...)) E {} d;");
   verifyFormat("enum struct __declspec__((...)) E {} d;");
   verifyFormat("enum struct X f() {\n  a();\n  return 42;\n}");
+
+  FormatStyle Style = getLLVMStyle();
+  Style.AllowShortEnumsOnASingleLine = false;
+  verifyFormat("enum struct Enum {\n"
+               "};",Style);
+  verifyFormat("enum struct {\n"
+               "};",Style);
+  verifyFormat("enum struct X E {\n"
+               "} d;",Style);
+  verifyFormat("enum struct __attribute__((...)) E {\n"
+               "} d;",Style);
+  verifyFormat("enum struct __declspec__((...)) E {\n"
+               "} d;",Style);
 }
 
 TEST_F(FormatTest, FormatsEnumClass) {
@@ -1883,6 +1914,19 @@
   verifyFormat("enum class __attribute__((...)) E {} d;");
   verifyFormat("enum class __declspec__((...)) E {} d;");
   verifyFormat("enum class X f() {\n  a();\n  return 42;\n}");
+
+  FormatStyle Style = getLLVMStyle();
+  Style.AllowShortEnumsOnASingleLine = false;
+  verifyFormat("enum class Enum {\n"
+               "};",Style);
+  verifyFormat("enum class {\n"
+               "};",Style);
+  verifyFormat("enum class X E {\n"
+               "} d;",Style);
+  verifyFormat("enum class __attribute__((...)) E {\n"
+               "} d;",Style);
+  verifyFormat("enum class __declspec__((...)) E {\n"
+               "} d;",Style);
 }
 
 TEST_F(FormatTest, FormatsEnumTypes) {
@@ -1892,6 +1936,17 @@
                "};");
   verifyFormat("enum X : int { A, B };");
   verifyFormat("enum X : std::uint32_t { A, B };");
+
+  FormatStyle Style = getLLVMStyle();
+  Style.AllowShortEnumsOnASingleLine = false;
+  verifyFormat("enum X : int {\n"
+               "  A,\n"
+	       "  B\n"
+	       "};",Style);
+  verifyFormat("enum X : std::uint32_t {\n"
+               "  A,\n"
+	       "  B\n"
+	       "};",Style);
 }
 
 TEST_F(FormatTest, FormatsTypedefEnum) {
@@ -1918,6 +1973,16 @@
                "  THREE = 3\n"
                "} LongEnum;",
                Style);
+
+  Style = getLLVMStyle();
+  Style.AllowShortEnumsOnASingleLine = false;
+  verifyFormat("typedef enum {\n"
+               "} EmptyEnum;",Style);
+  verifyFormat("typedef enum {\n"
+               "  A,\n"
+	       "  B,\n"
+	       "  C\n"
+	       "} ShortEnum;",Style);
 }
 
 TEST_F(FormatTest, FormatsNSEnums) {