Index: clang/lib/Format/ContinuationIndenter.cpp
===================================================================
--- clang/lib/Format/ContinuationIndenter.cpp
+++ clang/lib/Format/ContinuationIndenter.cpp
@@ -331,6 +331,15 @@
   if (Previous.is(tok::l_square) && Previous.is(TT_ObjCMethodExpr))
     return false;
 
+  if (Current.is(TT_ConditionalExpr) && Previous.is(tok::r_paren) &&
+      Previous.MatchingParen && Previous.MatchingParen->Previous &&
+      Previous.MatchingParen->Previous->is(tok::r_brace) &&
+      Previous.MatchingParen->Previous->MatchingParen &&
+      Previous.MatchingParen->Previous->MatchingParen->is(TT_LambdaLBrace)) {
+    // We have a lambda within a conditional expression, allow breaking here.
+    return true;
+  }
+
   return !CurrentState.NoLineBreak;
 }
 
Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -26549,6 +26549,54 @@
                Style);
 }
 
+TEST_F(FormatTest, MultilineLambdaInConditional) {
+  auto Style = getLLVMStyleWithColumns(70);
+  verifyFormat("auto aLengthyIdentifier = oneExpressionSoThatWeBreak ? []() {\n"
+               "  ;\n"
+               "  return 5;\n"
+               "}()\n"
+               "                                                     : 2;",
+               Style);
+  verifyFormat(
+      "auto aLengthyIdentifier = oneExpressionSoThatWeBreak ? 2 : []() {\n"
+      "  ;\n"
+      "  return 5;\n"
+      "}();",
+      Style);
+
+  Style = getLLVMStyleWithColumns(60);
+  verifyFormat("auto aLengthyIdentifier = oneExpressionSoThatWeBreak\n"
+               "                              ? []() {\n"
+               "                                  ;\n"
+               "                                  return 5;\n"
+               "                                }()\n"
+               "                              : 2;",
+               Style);
+  verifyFormat("auto aLengthyIdentifier =\n"
+               "    oneExpressionSoThatWeBreak ? 2 : []() {\n"
+               "      ;\n"
+               "      return 5;\n"
+               "    }();",
+               Style);
+
+  Style = getLLVMStyleWithColumns(40);
+  verifyFormat("auto aLengthyIdentifier =\n"
+               "    oneExpressionSoThatWeBreak ? []() {\n"
+               "      ;\n"
+               "      return 5;\n"
+               "    }()\n"
+               "                               : 2;",
+               Style);
+  verifyFormat("auto aLengthyIdentifier =\n"
+               "    oneExpressionSoThatWeBreak\n"
+               "        ? 2\n"
+               "        : []() {\n"
+               "            ;\n"
+               "            return 5;\n"
+               "          };",
+               Style);
+}
+
 TEST_F(FormatTest, AlignAfterOpenBracketBlockIndent) {
   auto Style = getLLVMStyle();