diff --git a/clang/docs/ClangFormatStyleOptions.rst b/clang/docs/ClangFormatStyleOptions.rst
--- a/clang/docs/ClangFormatStyleOptions.rst
+++ b/clang/docs/ClangFormatStyleOptions.rst
@@ -3085,8 +3085,8 @@
        #include "A/b.h"
        #include "B/a.h"
 
-  * ``SI_CaseInsensitive`` (in configuration: ``CaseInsensitive``)
-    Includes are sorted in an ASCIIbetical or case insensitive fashion.
+  * ``SI_CaseSensitive`` (in configuration: ``CaseSensitive``)
+    Includes are sorted in an ASCIIbetical or case sensitive fashion.
 
     .. code-block:: c++
 
@@ -3096,8 +3096,8 @@
        #include "B/a.h"
        #include "a/b.h"
 
-  * ``SI_CaseSensitive`` (in configuration: ``CaseSensitive``)
-    Includes are sorted in an alphabetical or case sensitive fashion.
+  * ``SI_CaseInsensitive`` (in configuration: ``CaseInsensitive``)
+    Includes are sorted in an alphabetical or case insensitive fashion.
 
     .. code-block:: c++
 
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -170,8 +170,8 @@
 
 - Option ``SortIncludes`` has been updated from a ``bool`` to an
   ``enum`` with backwards compatibility. In addition to the previous
-  ``true``/``false`` states (now ``CaseInsensitive``/``Never``), a third
-  state has been added (``CaseSensitive``) which causes an alphabetical sort
+  ``true``/``false`` states (now ``CaseSensitive``/``Never``), a third
+  state has been added (``CaseInsensitive``) which causes an alphabetical sort
   with case used as a tie-breaker.
 
   .. code-block:: c++
@@ -183,14 +183,14 @@
     #include "A/b.h"
     #include "B/a.h"
 
-    // CaseInsensitive (previously true)
+    // CaseSensitive (previously true)
     #include "A/B.h"
     #include "A/b.h"
     #include "B/A.h"
     #include "B/a.h"
     #include "a/b.h"
 
-    // CaseSensitive
+    // CaseInsensitive
     #include "A/B.h"
     #include "A/b.h"
     #include "a/b.h"
diff --git a/clang/include/clang/Format/Format.h b/clang/include/clang/Format/Format.h
--- a/clang/include/clang/Format/Format.h
+++ b/clang/include/clang/Format/Format.h
@@ -2679,7 +2679,7 @@
     ///    #include "B/a.h"
     /// \endcode
     SI_Never,
-    /// Includes are sorted in an ASCIIbetical or case insensitive fashion.
+    /// Includes are sorted in an ASCIIbetical or case sensitive fashion.
     /// \code
     ///    #include "A/B.h"
     ///    #include "A/b.h"
@@ -2687,8 +2687,8 @@
     ///    #include "B/a.h"
     ///    #include "a/b.h"
     /// \endcode
-    SI_CaseInsensitive,
-    /// Includes are sorted in an alphabetical or case sensitive fashion.
+    SI_CaseSensitive,
+    /// Includes are sorted in an alphabetical or case insensitive fashion.
     /// \code
     ///    #include "A/B.h"
     ///    #include "A/b.h"
@@ -2696,7 +2696,7 @@
     ///    #include "B/A.h"
     ///    #include "B/a.h"
     /// \endcode
-    SI_CaseSensitive,
+    SI_CaseInsensitive,
   };
 
   /// Controls if and how clang-format will sort ``#includes``.
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -423,7 +423,7 @@
 
     // For backward compatibility.
     IO.enumCase(Value, "false", FormatStyle::SI_Never);
-    IO.enumCase(Value, "true", FormatStyle::SI_CaseInsensitive);
+    IO.enumCase(Value, "true", FormatStyle::SI_CaseSensitive);
   }
 };
 
@@ -1047,7 +1047,7 @@
   LLVMStyle.PenaltyIndentedWhitespace = 0;
 
   LLVMStyle.DisableFormat = false;
-  LLVMStyle.SortIncludes = FormatStyle::SI_CaseInsensitive;
+  LLVMStyle.SortIncludes = FormatStyle::SI_CaseSensitive;
   LLVMStyle.SortJavaStaticImport = FormatStyle::SJSIO_Before;
   LLVMStyle.SortUsingDeclarations = true;
   LLVMStyle.StatementAttributeLikeMacros.push_back("Q_EMIT");
@@ -1250,7 +1250,7 @@
         "java",
         "javax",
     };
-    ChromiumStyle.SortIncludes = FormatStyle::SI_CaseInsensitive;
+    ChromiumStyle.SortIncludes = FormatStyle::SI_CaseSensitive;
   } else if (Language == FormatStyle::LK_JavaScript) {
     ChromiumStyle.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
     ChromiumStyle.AllowShortLoopsOnASingleLine = false;
@@ -2248,7 +2248,7 @@
     Indices.push_back(i);
   }
 
-  if (Style.SortIncludes == FormatStyle::SI_CaseSensitive) {
+  if (Style.SortIncludes == FormatStyle::SI_CaseInsensitive) {
     llvm::stable_sort(Indices, [&](unsigned LHSI, unsigned RHSI) {
       const auto LHSFilenameLower = Includes[LHSI].Filename.lower();
       const auto RHSFilenameLower = Includes[RHSI].Filename.lower();
diff --git a/clang/tools/clang-format/ClangFormat.cpp b/clang/tools/clang-format/ClangFormat.cpp
--- a/clang/tools/clang-format/ClangFormat.cpp
+++ b/clang/tools/clang-format/ClangFormat.cpp
@@ -404,7 +404,7 @@
 
   if (SortIncludes.getNumOccurrences() != 0) {
     if (SortIncludes)
-      FormatStyle->SortIncludes = FormatStyle::SI_CaseInsensitive;
+      FormatStyle->SortIncludes = FormatStyle::SI_CaseSensitive;
     else
       FormatStyle->SortIncludes = FormatStyle::SI_Never;
   }
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -16007,7 +16007,7 @@
 
   Style.SortIncludes = FormatStyle::SI_Never;
   CHECK_PARSE("SortIncludes: true", SortIncludes,
-              FormatStyle::SI_CaseInsensitive);
+              FormatStyle::SI_CaseSensitive);
   CHECK_PARSE("SortIncludes: false", SortIncludes, FormatStyle::SI_Never);
   CHECK_PARSE("SortIncludes: CaseInsensitive", SortIncludes,
               FormatStyle::SI_CaseInsensitive);
@@ -18131,7 +18131,7 @@
                             "#include \"b.h\"\n")});
 
   format::FormatStyle Style = format::getLLVMStyle();
-  Style.SortIncludes = FormatStyle::SI_CaseInsensitive;
+  Style.SortIncludes = FormatStyle::SI_CaseSensitive;
   auto FormattedReplaces = formatReplacements(Code, Replaces, Style);
   EXPECT_TRUE(static_cast<bool>(FormattedReplaces))
       << llvm::toString(FormattedReplaces.takeError()) << "\n";
diff --git a/clang/unittests/Format/SortIncludesTest.cpp b/clang/unittests/Format/SortIncludesTest.cpp
--- a/clang/unittests/Format/SortIncludesTest.cpp
+++ b/clang/unittests/Format/SortIncludesTest.cpp
@@ -599,9 +599,9 @@
 }
 
 TEST_F(SortIncludesTest, SupportOptionalCaseSensitiveSorting) {
-  EXPECT_FALSE(FmtStyle.SortIncludes == FormatStyle::SI_CaseSensitive);
+  EXPECT_FALSE(FmtStyle.SortIncludes == FormatStyle::SI_CaseInsensitive);
 
-  FmtStyle.SortIncludes = FormatStyle::SI_CaseSensitive;
+  FmtStyle.SortIncludes = FormatStyle::SI_CaseInsensitive;
 
   EXPECT_EQ("#include \"A/B.h\"\n"
             "#include \"A/b.h\"\n"