Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -2180,6 +2180,8 @@
   if (Left.opensScope()) {
     if (Style.AlignAfterOpenBracket == FormatStyle::BAS_DontAlign)
       return 0;
+    if (Left.Previous && Left.Previous->is(tok::equal))
+      return 19;
     return Left.ParameterCount > 1 ? Style.PenaltyBreakBeforeFirstCallParameter
                                    : 19;
   }
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -6650,6 +6650,15 @@
                "};");
   verifyFormat("#define A {a, a},");
 
+  // Avoid breaking between equal sign and opening brace
+  FormatStyle AvoidBreakingFirstArgument = getLLVMStyle();
+  AvoidBreakingFirstArgument.PenaltyBreakBeforeFirstCallParameter = 200;
+  verifyFormat("const std::unordered_map<std::string, int> MyHashTable = {\n"
+               "    {\"aaaaaaaaaaaaaaaaaaaaa\", 0},\n"
+               "    {\"bbbbbbbbbbbbbbbbbbbbb\", 1},\n"
+               "    {\"ccccccccccccccccccccc\", 2}};",
+               AvoidBreakingFirstArgument);
+
   // Binpacking only if there is no trailing comma
   verifyFormat("const Aaaaaa aaaaa = {aaaaaaaaaa, bbbbbbbbbb,\n"
                "                      cccccccccc, dddddddddd};",
@@ -6806,6 +6815,15 @@
   verifyFormat("vector<int> foo = { ::SomeGlobalFunction() };", ExtraSpaces);
   verifyFormat("const struct A a = { .a = 1, .b = 2 };", ExtraSpaces);
   verifyFormat("const struct A a = { [0] = 1, [1] = 2 };", ExtraSpaces);
+
+  // Avoid breaking between equal sign and opening brace
+  ExtraSpaces.PenaltyBreakBeforeFirstCallParameter = 200;
+  verifyFormat("const std::unordered_map<std::string, int> MyHashTable = {\n"
+               "  { \"aaaaaaaaaaaaaaaaaaaaa\", 0 },\n"
+               "  { \"bbbbbbbbbbbbbbbbbbbbb\", 1 },\n"
+               "  { \"ccccccccccccccccccccc\", 2 }\n"
+               "};",
+               ExtraSpaces);
 }
 
 TEST_F(FormatTest, FormatsBracedListsInColumnLayout) {
@@ -6867,6 +6885,14 @@
                "                 3, cccccccccccccccccccccc};",
                getLLVMStyleWithColumns(60));
 
+  // Do not break between equal and opening brace.
+  FormatStyle AvoidBreakingFirstArgument = getLLVMStyleWithColumns(43);
+  AvoidBreakingFirstArgument.PenaltyBreakBeforeFirstCallParameter = 200;
+  AvoidBreakingFirstArgument.ColumnLimit = 43;
+  verifyFormat("vector<int> aaaaaaaaaaaaaaaaaaaaaa = {\n"
+               "    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};",
+               AvoidBreakingFirstArgument);
+
   // Trailing commas.
   verifyFormat("vector<int> x = {\n"
                "    1, 1, 1, 1, 1, 1, 1, 1,\n"