Index: clang/lib/Format/WhitespaceManager.cpp
===================================================================
--- clang/lib/Format/WhitespaceManager.cpp
+++ clang/lib/Format/WhitespaceManager.cpp
@@ -957,7 +957,8 @@
     if (Style.AlignTrailingComments.Kind == FormatStyle::TCAS_Leave) {
       auto OriginalSpaces =
           Changes[i].OriginalWhitespaceRange.getEnd().getRawEncoding() -
-          Changes[i].OriginalWhitespaceRange.getBegin().getRawEncoding();
+          Changes[i].OriginalWhitespaceRange.getBegin().getRawEncoding() -
+          Changes[i].NewlinesBefore;
       unsigned RestoredLineLength = Changes[i].StartOfTokenColumn +
                                     Changes[i].TokenLength + OriginalSpaces;
       // If leaving comments makes the line exceed the column limit, give up to
Index: clang/unittests/Format/FormatTestComments.cpp
===================================================================
--- clang/unittests/Format/FormatTestComments.cpp
+++ clang/unittests/Format/FormatTestComments.cpp
@@ -3062,6 +3062,18 @@
                    "int d;// comment\n",
                    Style));
 
+  EXPECT_EQ("// do not touch\n"
+            "int a;  // any comments\n\n"
+            "   // comment\n"
+            "// comment\n\n"
+            "// comment\n",
+            format("// do not touch\n"
+                   "int a;  // any comments\n\n"
+                   "   // comment\n"
+                   "// comment\n\n"
+                   "// comment\n",
+                   Style));
+
   // Just format comments normally when leaving exceeds the column limit
   Style.ColumnLimit = 35;
   EXPECT_EQ("int foo = 12345; // comment\n"