Index: lib/Format/ContinuationIndenter.cpp
===================================================================
--- lib/Format/ContinuationIndenter.cpp
+++ lib/Format/ContinuationIndenter.cpp
@@ -1840,7 +1840,8 @@
         // No break opportunity - update the penalty and continue with the next
         // logical line.
         if (LineIndex < EndIndex - 1)
-          // The last line's penalty is handled in addNextStateToQueue().
+          // The last line's penalty is handled in addNextStateToQueue() or when
+          // calling replaceWhitespaceAfterLastLine below.
           Penalty += Style.PenaltyExcessCharacter *
                      (ContentStartColumn + RemainingTokenColumns - ColumnLimit);
         LLVM_DEBUG(llvm::dbgs() << "    No break opportunity.\n");
@@ -2095,6 +2096,12 @@
       Token->getSplitAfterLastLine(TailOffset);
   if (SplitAfterLastLine.first != StringRef::npos) {
     LLVM_DEBUG(llvm::dbgs() << "Replacing whitespace after last line.\n");
+
+    // We add the last line's penalty here, since that line is going to be split
+    // now.
+    Penalty += Style.PenaltyExcessCharacter *
+               (ContentStartColumn + RemainingTokenColumns - ColumnLimit);
+
     if (!DryRun)
       Token->replaceWhitespaceAfterLastLine(TailOffset, SplitAfterLastLine,
                                             Whitespaces);
Index: unittests/Format/FormatTestJS.cpp
===================================================================
--- unittests/Format/FormatTestJS.cpp
+++ unittests/Format/FormatTestJS.cpp
@@ -2284,5 +2284,25 @@
                "formatMe( );\n");
 }
 
+TEST_F(FormatTestJS, AddsLastLinePenaltyIfEndingIsBroken) {
+  EXPECT_EQ(
+      "a = function() {\n"
+      "  b = function() {\n"
+      "    this.aaaaaaaaaaaaaaaaaaa[aaaaaaaaaaa] = aaaa.aaaaaa ?\n"
+      "        aaaa.aaaaaa : /** @type "
+      "{aaaa.aaaa.aaaaaaaaa.aaaaaaaaaaaaaaaaaaa} */\n"
+      "        (aaaa.aaaa.aaaaaaaaa.aaaaaaaaaaaaa.aaaaaaaaaaaaaaaaa);\n"
+      "  };\n"
+      "};",
+      format("a = function() {\n"
+             "  b = function() {\n"
+             "    this.aaaaaaaaaaaaaaaaaaa[aaaaaaaaaaa] = aaaa.aaaaaa ? "
+             "aaaa.aaaaaa : /** @type "
+             "{aaaa.aaaa.aaaaaaaaa.aaaaaaaaaaaaaaaaaaa} */\n"
+             "        (aaaa.aaaa.aaaaaaaaa.aaaaaaaaaaaaa.aaaaaaaaaaaaaaaaa);\n"
+             "  };\n"
+             "};"));
+}
+
 } // end namespace tooling
 } // end namespace clang