Index: docs/ClangFormatStyleOptions.rst
===================================================================
--- docs/ClangFormatStyleOptions.rst
+++ docs/ClangFormatStyleOptions.rst
@@ -394,6 +394,12 @@
     (https://developers.google.com/protocol-buffers/).
 
 
+**MacroBlockBegin** (``std::string``)
+  A regular expression matching macros that start a block.
+
+**MacroBlockEnd** (``std::string``)
+  A regular expression matching macros that end a block.
+
 **MaxEmptyLinesToKeep** (``unsigned``)
   The maximum number of consecutive empty lines to keep.
 
Index: include/clang/Format/Format.h
===================================================================
--- include/clang/Format/Format.h
+++ include/clang/Format/Format.h
@@ -290,6 +290,12 @@
   /// \brief Language, this format style is targeted at.
   LanguageKind Language;
 
+  /// \brief A regular expression matching macros that start a block.
+  std::string MacroBlockBegin;
+
+  /// \brief A regular expression matching macros that end a block.
+  std::string MacroBlockEnd;
+
   /// \brief The maximum number of consecutive empty lines to keep.
   unsigned MaxEmptyLinesToKeep;
 
@@ -479,6 +485,8 @@
            IndentWrappedFunctionNames == R.IndentWrappedFunctionNames &&
            KeepEmptyLinesAtTheStartOfBlocks ==
                R.KeepEmptyLinesAtTheStartOfBlocks &&
+           MacroBlockBegin == R.MacroBlockBegin &&
+           MacroBlockEnd == R.MacroBlockEnd &&
            MaxEmptyLinesToKeep == R.MaxEmptyLinesToKeep &&
            NamespaceIndentation == R.NamespaceIndentation &&
            ObjCBlockIndentWidth == R.ObjCBlockIndentWidth &&
Index: lib/Format/Format.cpp
===================================================================
--- lib/Format/Format.cpp
+++ lib/Format/Format.cpp
@@ -27,6 +27,7 @@
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/Regex.h"
 #include "llvm/Support/YAMLTraits.h"
 #include <queue>
 #include <string>
@@ -244,6 +245,8 @@
                    Style.IndentWrappedFunctionNames);
     IO.mapOptional("KeepEmptyLinesAtTheStartOfBlocks",
                    Style.KeepEmptyLinesAtTheStartOfBlocks);
+    IO.mapOptional("MacroBlockBegin", Style.MacroBlockBegin);
+    IO.mapOptional("MacroBlockEnd", Style.MacroBlockEnd);
     IO.mapOptional("MaxEmptyLinesToKeep", Style.MaxEmptyLinesToKeep);
     IO.mapOptional("NamespaceIndentation", Style.NamespaceIndentation);
     IO.mapOptional("ObjCBlockIndentWidth", Style.ObjCBlockIndentWidth);
@@ -468,6 +471,8 @@
     ChromiumStyle.BinPackParameters = false;
     ChromiumStyle.DerivePointerAlignment = false;
   }
+  ChromiumStyle.MacroBlockBegin = "^IPC_BEGIN_MESSAGE_MAP$";
+  ChromiumStyle.MacroBlockBegin = "^IPC_END_MESSAGE_MAP$";
   return ChromiumStyle;
 }
 
@@ -620,7 +625,9 @@
         LessStashed(false), Column(0), TrailingWhitespace(0),
         SourceMgr(SourceMgr), ID(ID), Style(Style),
         IdentTable(getFormattingLangOpts(Style)), Keywords(IdentTable),
-        Encoding(Encoding), FirstInLineIndex(0), FormattingDisabled(false) {
+        Encoding(Encoding), FirstInLineIndex(0), FormattingDisabled(false),
+        MacroBlockBeginRegex(Style.MacroBlockBegin),
+        MacroBlockEndRegex(Style.MacroBlockEnd) {
     Lex.reset(new Lexer(ID, SourceMgr.getBuffer(ID), SourceMgr,
                         getFormattingLangOpts(Style)));
     Lex->SetKeepWhitespaceMode(true);
@@ -1160,12 +1167,21 @@
       Column = FormatTok->LastLineColumnWidth;
     }
 
-    if (!(Tokens.size() > 0 && Tokens.back()->Tok.getIdentifierInfo() &&
-          Tokens.back()->Tok.getIdentifierInfo()->getPPKeywordID() ==
-              tok::pp_define) &&
-        std::find(ForEachMacros.begin(), ForEachMacros.end(),
-                  FormatTok->Tok.getIdentifierInfo()) != ForEachMacros.end())
-      FormatTok->Type = TT_ForEachMacro;
+    if (Style.Language == FormatStyle::LK_Cpp) {
+      if (!(Tokens.size() > 0 && Tokens.back()->Tok.getIdentifierInfo() &&
+            Tokens.back()->Tok.getIdentifierInfo()->getPPKeywordID() ==
+                tok::pp_define) &&
+          std::find(ForEachMacros.begin(), ForEachMacros.end(),
+                    FormatTok->Tok.getIdentifierInfo()) != ForEachMacros.end()) {
+        FormatTok->Type = TT_ForEachMacro;
+      } else if (FormatTok->is(tok::identifier)) {
+        if (MacroBlockBeginRegex.match(Text)) {
+          FormatTok->Type = TT_MacroBlockBegin;
+        } else if (MacroBlockEndRegex.match(Text)) {
+          FormatTok->Type = TT_MacroBlockEnd;
+        }
+      }
+    }
 
     return FormatTok;
   }
@@ -1190,6 +1206,9 @@
 
   bool FormattingDisabled;
 
+  llvm::Regex MacroBlockBeginRegex;
+  llvm::Regex MacroBlockEndRegex;
+
   void readRawToken(FormatToken &Tok) {
     Lex->LexFromRawLexer(Tok.Tok);
     Tok.TokenText = StringRef(SourceMgr.getCharacterData(Tok.Tok.getLocation()),
Index: lib/Format/FormatToken.h
===================================================================
--- lib/Format/FormatToken.h
+++ lib/Format/FormatToken.h
@@ -59,6 +59,8 @@
   TT_LambdaLSquare,
   TT_LeadingJavaAnnotation,
   TT_LineComment,
+  TT_MacroBlockBegin,
+  TT_MacroBlockEnd,
   TT_ObjCBlockLBrace,
   TT_ObjCBlockLParen,
   TT_ObjCDecl,
Index: lib/Format/UnwrappedLineParser.cpp
===================================================================
--- lib/Format/UnwrappedLineParser.cpp
+++ lib/Format/UnwrappedLineParser.cpp
@@ -269,7 +269,14 @@
 void UnwrappedLineParser::parseLevel(bool HasOpeningBrace) {
   bool SwitchLabelEncountered = false;
   do {
-    switch (FormatTok->Tok.getKind()) {
+    tok::TokenKind kind = FormatTok->Tok.getKind();
+    if (FormatTok->Type == TT_MacroBlockBegin) {
+      kind = tok::l_brace;
+    } else if (FormatTok->Type == TT_MacroBlockEnd) {
+      kind = tok::r_brace;
+    }
+
+    switch (kind) {
     case tok::comment:
       nextToken();
       addUnwrappedLine();
@@ -393,10 +400,16 @@
 
 void UnwrappedLineParser::parseBlock(bool MustBeDeclaration, bool AddLevel,
                                      bool MunchSemi) {
-  assert(FormatTok->Tok.is(tok::l_brace) && "'{' expected");
+  assert(FormatTok->isOneOf(tok::l_brace, TT_MacroBlockBegin) &&
+         "'{' or macro block token expected");
+  const bool MacroBlock = FormatTok->is(TT_MacroBlockBegin);
+
   unsigned InitialLevel = Line->Level;
   nextToken();
 
+  if (MacroBlock && FormatTok->is(tok::l_paren))
+    parseParens();
+
   addUnwrappedLine();
 
   ScopedDeclarationState DeclarationState(*Line, DeclarationScopeStack,
@@ -405,12 +418,17 @@
     ++Line->Level;
   parseLevel(/*HasOpeningBrace=*/true);
 
-  if (!FormatTok->Tok.is(tok::r_brace)) {
+  if (MacroBlock ? !FormatTok->is(TT_MacroBlockEnd)
+                 : !FormatTok->is(tok::r_brace)) {
     Line->Level = InitialLevel;
     return;
   }
 
   nextToken(); // Munch the closing brace.
+
+  if (MacroBlock && FormatTok->is(tok::l_paren))
+    parseParens();
+
   if (MunchSemi && FormatTok->Tok.is(tok::semi))
     nextToken();
   Line->Level = InitialLevel;
@@ -757,6 +775,11 @@
       parseForOrWhileLoop();
       return;
     }
+    if (FormatTok->is(TT_MacroBlockBegin)) {
+      parseBlock(/*MustBeDeclaration=*/false, /*AddLevel=*/true,
+                 /*MunchSemi=*/false);
+      return;
+    }
     if (Style.Language == FormatStyle::LK_JavaScript &&
         FormatTok->is(Keywords.kw_import)) {
       parseJavaScriptEs6ImportExport();
@@ -860,6 +883,11 @@
       parseTryCatch();
       return;
     case tok::identifier: {
+      if (FormatTok->is(TT_MacroBlockEnd)) {
+        addUnwrappedLine();
+        return;
+      }
+
       // Parse function literal unless 'function' is the first token in a line
       // in which case this should be treated as a free-standing function.
       if (Style.Language == FormatStyle::LK_JavaScript &&
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -3214,6 +3214,24 @@
   verifyFormat("enum E {}");
 }
 
+TEST_F(FormatTest, FormatBeginBlockEndMacros) {
+  FormatStyle Style = getLLVMStyle();
+  Style.MacroBlockBegin = "^[A-Z_]+_BEGIN$";
+  Style.MacroBlockEnd = "^[A-Z_]+_END$";
+  verifyFormat("FOO_BEGIN\n"
+               "  FOO_ENTRY\n"
+               "FOO_END", Style);
+  verifyFormat("FOO_BEGIN\n"
+               "  NESTED_FOO_BEGIN\n"
+               "    NESTED_FOO_ENTRY\n"
+               "  NESTED_FOO_END\n"
+               "FOO_END", Style);
+  verifyFormat("FOO_BEGIN(Foo, Bar)\n"
+               "  int x;\n"
+               "  x = 1;\n"
+               "FOO_END(Baz)", Style);
+}
+
 //===----------------------------------------------------------------------===//
 // Line break tests.
 //===----------------------------------------------------------------------===//