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
@@ -492,6 +492,9 @@
   // update information about whether an lbrace starts a
   // braced init list or a different block during the loop.
   SmallVector<FormatToken *, 8> LBraceStack;
+  // Track the previous token type corresponding to our lbraces // to help
+  // detect brace types
+  SmallVector<tok::TokenKind, 8> PrevTokenKindStack;
   assert(Tok->is(tok::l_brace));
   do {
     // Get next non-comment token.
@@ -522,6 +525,8 @@
         Tok->setBlockKind(BK_Unknown);
       }
       LBraceStack.push_back(Tok);
+      PrevTokenKindStack.push_back(PrevTok ? PrevTok->Tok.getKind()
+                                           : tok::unknown);
       break;
     case tok::r_brace:
       if (LBraceStack.empty())
@@ -570,8 +575,13 @@
           ProbablyBracedList =
               ProbablyBracedList ||
               NextTok->isOneOf(tok::comma, tok::period, tok::colon,
-                               tok::r_paren, tok::r_square, tok::l_brace,
-                               tok::ellipsis);
+                               tok::r_paren, tok::r_square, tok::ellipsis);
+
+          // Distinguish between braced list in a constructor initializer list
+          // followed by constructor body, or just adjacent blocks
+          ProbablyBracedList = ProbablyBracedList ||
+                               NextTok->is(tok::l_brace) &&
+                                   PrevTokenKindStack.back() == tok::identifier;
 
           ProbablyBracedList =
               ProbablyBracedList ||
@@ -602,6 +612,7 @@
         }
       }
       LBraceStack.pop_back();
+      PrevTokenKindStack.pop_back();
       break;
     case tok::identifier:
       if (!Tok->is(TT_StatementMacro))
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
@@ -13731,6 +13731,26 @@
                "  struct Dummy {};\n"
                "  f(v);\n"
                "}");
+  verifyFormat("void foo() {\n"
+               "  { // asdf\n"
+               "    { int a; }\n"
+               "  }\n"
+               "  {\n"
+               "    { int b; }\n"
+               "  }\n"
+               "}");
+  verifyFormat("namespace n {\n"
+               "void foo() {\n"
+               "  {\n"
+               "    {\n"
+               "      statement();\n"
+               "      if (false) {\n"
+               "      }\n"
+               "    }\n"
+               "  }\n"
+               "  {}\n"
+               "}\n"
+               "} // namespace n");
 
   // Long lists should be formatted in columns even if they are nested.
   verifyFormat(