Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -142,8 +142,32 @@
 
     bool StartsObjCMethodExpr = false;
     if (CurrentToken->is(tok::caret)) {
-      // (^ can start a block type.
-      Left->Type = TT_ObjCBlockLParen;
+      // The following are valid ObjC block types and block variables:
+      //
+      // int (^)(char, float)
+      // int (^block)(char, float)
+      // int (^arrayOfTenBlocks[10])(char, float)
+      // int (^arrayOfManyBlocks[(kLen + 42)])(char, float)
+      const FormatToken *Next = CurrentToken->getNextNonComment();
+      int ParenDepth = 1;
+      // Handle nested parens in case we have an array of blocks with
+      // a parenthesized length.
+      while (Next) {
+        if (Next->is(tok::l_paren))
+          ++ParenDepth;
+        else if (Next->is(tok::r_paren))
+          --ParenDepth;
+        if (ParenDepth == 0)
+          break;
+        Next = Next->getNextNonComment();
+      }
+      if (Next) {
+        const FormatToken *NextNext = Next->getNextNonComment();
+        // If we have an opening paren at the end of (^...)( we assume
+        // we have an Objective-C block.
+        if (NextNext && NextNext->is(tok::l_paren))
+          Left->Type = TT_ObjCBlockLParen;
+      }
     } else if (FormatToken *MaybeSel = Left->Previous) {
       // @selector( starts a selector.
       if (MaybeSel->isObjCAtKeyword(tok::objc_selector) && MaybeSel->Previous &&
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -12128,6 +12128,22 @@
   EXPECT_EQ(FormatStyle::LK_Cpp, guessLanguage("foo.h", "[[foo::bar, ...]]"));
 }
 
+TEST_F(FormatTest, GuessLanguageWithCaret) {
+  EXPECT_EQ(FormatStyle::LK_Cpp, guessLanguage("foo.h", "FOO(^);"));
+  EXPECT_EQ(FormatStyle::LK_Cpp, guessLanguage("foo.h", "FOO(^, Bar);"));
+  EXPECT_EQ(FormatStyle::LK_ObjC,
+            guessLanguage("foo.h", "int(^)(char, float);"));
+  EXPECT_EQ(FormatStyle::LK_ObjC,
+            guessLanguage("foo.h", "int(^foo)(char, float);"));
+  EXPECT_EQ(FormatStyle::LK_ObjC,
+            guessLanguage("foo.h", "int(^foo[10])(char, float);"));
+  EXPECT_EQ(FormatStyle::LK_ObjC,
+            guessLanguage("foo.h", "int(^foo[kNumEntries])(char, float);"));
+  EXPECT_EQ(
+      FormatStyle::LK_ObjC,
+      guessLanguage("foo.h", "int(^foo[(kNumEntries + 10)])(char, float);"));
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang
Index: unittests/Format/FormatTestObjC.cpp
===================================================================
--- unittests/Format/FormatTestObjC.cpp
+++ unittests/Format/FormatTestObjC.cpp
@@ -845,6 +845,15 @@
   verifyFormat("@ /*foo*/ interface");
 }
 
+TEST_F(FormatTestObjC, ObjCBlockTypesAndVariables) {
+  verifyFormat("void DoStuffWithBlockType(int (^)(char));");
+  verifyFormat("int (^foo)(char, float);");
+  verifyFormat("int (^foo[10])(char, float);");
+  verifyFormat("int (^foo[kNumEntries])(char, float);");
+  verifyFormat("int (^foo[kNumEntries + 10])(char, float);");
+  verifyFormat("int (^foo[(kNumEntries + 10)])(char, float);");
+}
+
 TEST_F(FormatTestObjC, ObjCSnippets) {
   verifyFormat("@autoreleasepool {\n"
                "  foo();\n"