Index: cfe/trunk/docs/ClangFormatStyleOptions.rst
===================================================================
--- cfe/trunk/docs/ClangFormatStyleOptions.rst
+++ cfe/trunk/docs/ClangFormatStyleOptions.rst
@@ -1511,6 +1511,13 @@
   can also assign negative priorities if you have certain headers that
   always need to be first.
 
+  There is a third and optional field ``SortPriority`` which can used while
+  ``IncludeBloks = IBS_Regroup`` to define the priority in which ``#includes``
+  should be ordered, and value of ``Priority`` defines the order of
+  ``#include blocks`` and also enables to group ``#includes`` of different
+  priority for order.``SortPriority`` is set to the value of ``Priority``
+  as default if it is not assigned.
+
   To configure this in the .clang-format file, use:
 
   .. code-block:: yaml
@@ -1518,12 +1525,14 @@
     IncludeCategories:
       - Regex:           '^"(llvm|llvm-c|clang|clang-c)/'
         Priority:        2
+        SortPriority:    2
       - Regex:           '^(<|"(gtest|gmock|isl|json)/)'
         Priority:        3
       - Regex:           '<[[:alnum:].]+>'
         Priority:        4
       - Regex:           '.*'
         Priority:        1
+        SortPriority:    0
 
 **IncludeIsMainRegex** (``std::string``)
   Specify a regular expression of suffixes that are allowed in the
Index: cfe/trunk/include/clang/Tooling/Inclusions/HeaderIncludes.h
===================================================================
--- cfe/trunk/include/clang/Tooling/Inclusions/HeaderIncludes.h
+++ cfe/trunk/include/clang/Tooling/Inclusions/HeaderIncludes.h
@@ -32,6 +32,7 @@
   /// 0. Otherwise, returns the priority of the matching category or INT_MAX.
   /// NOTE: this API is not thread-safe!
   int getIncludePriority(StringRef IncludeName, bool CheckMainHeader) const;
+  int getSortIncludePriority(StringRef IncludeName, bool CheckMainHeader) const;
 
 private:
   bool isMainHeader(StringRef IncludeName) const;
Index: cfe/trunk/include/clang/Tooling/Inclusions/IncludeStyle.h
===================================================================
--- cfe/trunk/include/clang/Tooling/Inclusions/IncludeStyle.h
+++ cfe/trunk/include/clang/Tooling/Inclusions/IncludeStyle.h
@@ -58,6 +58,8 @@
     std::string Regex;
     /// The priority to assign to this category.
     int Priority;
+    /// The custom priority to sort before grouping.
+    int SortPriority;
     bool operator==(const IncludeCategory &Other) const {
       return Regex == Other.Regex && Priority == Other.Priority;
     }
Index: cfe/trunk/lib/Format/Format.cpp
===================================================================
--- cfe/trunk/lib/Format/Format.cpp
+++ cfe/trunk/lib/Format/Format.cpp
@@ -1771,6 +1771,7 @@
   StringRef Text;
   unsigned Offset;
   int Category;
+  int Priority;
 };
 
 struct JavaImportDirective {
@@ -1834,6 +1835,7 @@
                             ArrayRef<tooling::Range> Ranges, StringRef FileName,
                             StringRef Code, tooling::Replacements &Replaces,
                             unsigned *Cursor) {
+  tooling::IncludeCategoryManager Categories(Style.IncludeStyle, FileName);
   unsigned IncludesBeginOffset = Includes.front().Offset;
   unsigned IncludesEndOffset =
       Includes.back().Offset + Includes.back().Text.size();
@@ -1841,11 +1843,12 @@
   if (!affectsRange(Ranges, IncludesBeginOffset, IncludesEndOffset))
     return;
   SmallVector<unsigned, 16> Indices;
-  for (unsigned i = 0, e = Includes.size(); i != e; ++i)
+  for (unsigned i = 0, e = Includes.size(); i != e; ++i) {
     Indices.push_back(i);
+  }
   llvm::stable_sort(Indices, [&](unsigned LHSI, unsigned RHSI) {
-    return std::tie(Includes[LHSI].Category, Includes[LHSI].Filename) <
-           std::tie(Includes[RHSI].Category, Includes[RHSI].Filename);
+    return std::tie(Includes[LHSI].Priority, Includes[LHSI].Filename) <
+           std::tie(Includes[RHSI].Priority, Includes[RHSI].Filename);
   });
   // The index of the include on which the cursor will be put after
   // sorting/deduplicating.
@@ -1960,9 +1963,12 @@
         int Category = Categories.getIncludePriority(
             IncludeName,
             /*CheckMainHeader=*/!MainIncludeFound && FirstIncludeBlock);
+        int Priority = Categories.getSortIncludePriority(
+            IncludeName, !MainIncludeFound && FirstIncludeBlock);
         if (Category == 0)
           MainIncludeFound = true;
-        IncludesInBlock.push_back({IncludeName, Line, Prev, Category});
+        IncludesInBlock.push_back(
+            {IncludeName, Line, Prev, Category, Priority});
       } else if (!IncludesInBlock.empty() && !EmptyLineSkipped) {
         sortCppIncludes(Style, IncludesInBlock, Ranges, FileName, Code,
                         Replaces, Cursor);
Index: cfe/trunk/lib/Tooling/Inclusions/HeaderIncludes.cpp
===================================================================
--- cfe/trunk/lib/Tooling/Inclusions/HeaderIncludes.cpp
+++ cfe/trunk/lib/Tooling/Inclusions/HeaderIncludes.cpp
@@ -199,6 +199,20 @@
   return Ret;
 }
 
+int IncludeCategoryManager::getSortIncludePriority(StringRef IncludeName,
+                                                   bool CheckMainHeader) const {
+  int Ret = INT_MAX;
+  for (unsigned i = 0, e = CategoryRegexs.size(); i != e; ++i)
+    if (CategoryRegexs[i].match(IncludeName)) {
+      Ret = Style.IncludeCategories[i].SortPriority;
+      if (Ret == 0)
+        Ret = Style.IncludeCategories[i].Priority;
+      break;
+    }
+  if (CheckMainHeader && IsMainFile && Ret > 0 && isMainHeader(IncludeName))
+    Ret = 0;
+  return Ret;
+}
 bool IncludeCategoryManager::isMainHeader(StringRef IncludeName) const {
   if (!IncludeName.startswith("\""))
     return false;
Index: cfe/trunk/lib/Tooling/Inclusions/IncludeStyle.cpp
===================================================================
--- cfe/trunk/lib/Tooling/Inclusions/IncludeStyle.cpp
+++ cfe/trunk/lib/Tooling/Inclusions/IncludeStyle.cpp
@@ -17,6 +17,7 @@
     IO &IO, IncludeStyle::IncludeCategory &Category) {
   IO.mapOptional("Regex", Category.Regex);
   IO.mapOptional("Priority", Category.Priority);
+  IO.mapOptional("SortPriority", Category.SortPriority);
 }
 
 void ScalarEnumerationTraits<IncludeStyle::IncludeBlocksStyle>::enumeration(
Index: cfe/trunk/unittests/Format/SortIncludesTest.cpp
===================================================================
--- cfe/trunk/unittests/Format/SortIncludesTest.cpp
+++ cfe/trunk/unittests/Format/SortIncludesTest.cpp
@@ -70,6 +70,77 @@
                  {tooling::Range(25, 1)}));
 }
 
+TEST_F(SortIncludesTest, SortedIncludesUsingSortPriorityAttribute) {
+  FmtStyle.IncludeStyle.IncludeBlocks = tooling::IncludeStyle::IBS_Regroup;
+  FmtStyle.IncludeStyle.IncludeCategories = {
+      {"^<sys/param\\.h>", 1, 0},
+      {"^<sys/types\\.h>", 1, 1},
+      {"^<sys.*/", 1, 2},
+      {"^<uvm/", 2, 3},
+      {"^<machine/", 3, 4},
+      {"^<dev/", 4, 5},
+      {"^<net.*/", 5, 6},
+      {"^<protocols/", 5, 7},
+      {"^<(fs|miscfs|msdosfs|nfs|ntfs|ufs)/", 6, 8},
+      {"^<(x86|amd64|i386|xen)/", 7, 8},
+      {"<path", 9, 11},
+      {"^<[^/].*\\.h>", 8, 10},
+      {"^\".*\\.h\"", 10, 12}};
+  EXPECT_EQ("#include <sys/param.h>\n"
+            "#include <sys/types.h>\n"
+            "#include <sys/ioctl.h>\n"
+            "#include <sys/socket.h>\n"
+            "#include <sys/stat.h>\n"
+            "#include <sys/wait.h>\n"
+            "\n"
+            "#include <net/if.h>\n"
+            "#include <net/if_dl.h>\n"
+            "#include <net/route.h>\n"
+            "#include <netinet/in.h>\n"
+            "#include <protocols/rwhod.h>\n"
+            "\n"
+            "#include <assert.h>\n"
+            "#include <errno.h>\n"
+            "#include <inttypes.h>\n"
+            "#include <stdio.h>\n"
+            "#include <stdlib.h>\n"
+            "\n"
+            "#include <paths.h>\n"
+            "\n"
+            "#include \"pathnames.h\"\n",
+            sort("#include <sys/param.h>\n"
+                 "#include <sys/types.h>\n"
+                 "#include <sys/ioctl.h>\n"
+                 "#include <net/if_dl.h>\n"
+                 "#include <net/route.h>\n"
+                 "#include <netinet/in.h>\n"
+                 "#include <sys/socket.h>\n"
+                 "#include <sys/stat.h>\n"
+                 "#include <sys/wait.h>\n"
+                 "#include <net/if.h>\n"
+                 "#include <protocols/rwhod.h>\n"
+                 "#include <assert.h>\n"
+                 "#include <paths.h>\n"
+                 "#include \"pathnames.h\"\n"
+                 "#include <errno.h>\n"
+                 "#include <inttypes.h>\n"
+                 "#include <stdio.h>\n"
+                 "#include <stdlib.h>\n"));
+}
+TEST_F(SortIncludesTest, SortPriorityNotDefined) {
+  FmtStyle = getLLVMStyle();
+  EXPECT_EQ("#include \"FormatTestUtils.h\"\n"
+            "#include \"clang/Format/Format.h\"\n"
+            "#include \"llvm/ADT/None.h\"\n"
+            "#include \"llvm/Support/Debug.h\"\n"
+            "#include \"gtest/gtest.h\"\n",
+            sort("#include \"clang/Format/Format.h\"\n"
+                 "#include \"llvm/ADT/None.h\"\n"
+                 "#include \"FormatTestUtils.h\"\n"
+                 "#include \"gtest/gtest.h\"\n"
+                 "#include \"llvm/Support/Debug.h\"\n"));
+}
+
 TEST_F(SortIncludesTest, NoReplacementsForValidIncludes) {
   // Identical #includes have led to a failure with an unstable sort.
   std::string Code = "#include <a>\n"