Index: clang/lib/Format/Format.cpp
===================================================================
--- clang/lib/Format/Format.cpp
+++ clang/lib/Format/Format.cpp
@@ -2307,8 +2307,8 @@
         IncludesInBlock.clear();
         FirstIncludeBlock = false;
       }
-      Prev = Pos + 1;
     }
+    Prev = Pos + 1;
     if (Pos == StringRef::npos || Pos + 1 == Code.size())
       break;
     SearchFrom = Pos + 1;
Index: clang/test/Format/line-disable-include-sorting.cpp
===================================================================
--- /dev/null
+++ clang/test/Format/line-disable-include-sorting.cpp
@@ -0,0 +1,13 @@
+// RUN: grep -Ev "// *[A-Z-]+:" %s \
+// RUN:   | clang-format -style="{BasedOnStyle: LLVM, SortIncludes: true}" \
+// RUN:   | FileCheck -strict-whitespace %s
+// CHECK: {{^//\ clang-format\ off$}}
+// CHECK-NEXT: {{^#include\ <c>$}}
+// CHECK-NEXT: {{^//\ clang-format\ on$}}
+// CHECK-NEXT: {{^#include\ <a>$}}
+// CHECK-NEXT: {{^#include\ <b>$}}
+// clang-format off
+#include <c>
+// clang-format on
+#include <b>
+#include <a>