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
@@ -14,6 +14,7 @@
 
 #include "UnwrappedLineParser.h"
 #include "FormatToken.h"
+#include "clang/Basic/TokenKinds.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -1007,7 +1008,7 @@
 
   if (!Tok->isOneOf(tok::kw_int, tok::kw_char, tok::kw_float, tok::kw_double,
                     tok::kw_struct, tok::kw_union, tok::kw_long, tok::kw_short,
-                    tok::kw_unsigned, tok::kw_register, tok::identifier))
+                    tok::kw_unsigned, tok::kw_register))
     return false;
 
   Tok = Tok->Previous;
@@ -1378,7 +1379,8 @@
         break;
       if (Previous->Previous && Previous->Previous->is(tok::at))
         break;
-      if (isC78ParameterDecl(FormatTok)) {
+      if (!Line->Tokens.begin()->Tok->is(tok::kw_typedef) &&
+          isC78ParameterDecl(FormatTok)) {
         addUnwrappedLine();
         return;
       }
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
@@ -8247,14 +8247,25 @@
                "  return a + b < c;\n"
                "};",
                Style);
-  // The return breaking style doesn't affect object definitions with
-  // attribute-like macros.
+
+  // The return breaking style doesn't affect:
+  // * function and object definitions with attribute-like macros
   verifyFormat("Tttttttttttttttttttttttt ppppppppppppppp\n"
                "    ABSL_GUARDED_BY(mutex) = {};",
                getGoogleStyleWithColumns(40));
   verifyFormat("Tttttttttttttttttttttttt ppppppppppppppp\n"
                "    ABSL_GUARDED_BY(mutex);  // comment",
                getGoogleStyleWithColumns(40));
+  verifyFormat("Tttttttttttttttttttttttt ppppppppppppppp\n"
+               "    ABSL_GUARDED_BY(mutex1)\n"
+               "        ABSL_GUARDED_BY(mutex2);",
+               getGoogleStyleWithColumns(40));
+  verifyFormat("Tttttt f(int a, int b)\n"
+               "    ABSL_GUARDED_BY(mutex1)\n"
+               "        ABSL_GUARDED_BY(mutex2);",
+               getGoogleStyleWithColumns(40));
+  // * typedefs
+  verifyFormat("typedef ATTR(X) char x;", getGoogleStyle());
 
   Style = getGNUStyle();