Index: clang/lib/Analysis/CMakeLists.txt
===================================================================
--- clang/lib/Analysis/CMakeLists.txt
+++ clang/lib/Analysis/CMakeLists.txt
@@ -39,6 +39,7 @@
   clangASTMatchers
   clangBasic
   clangLex
+  clangToolingInclusions
 
   DEPENDS
   omp_gen
Index: clang/lib/Analysis/UnsafeBufferUsage.cpp
===================================================================
--- clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -9,7 +9,10 @@
 #include "clang/Analysis/Analyses/UnsafeBufferUsage.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Basic/SourceLocation.h"
 #include "clang/Lex/Lexer.h"
+#include "clang/Tooling/Inclusions/HeaderIncludes.h"
+#include "clang/Tooling/Inclusions/IncludeStyle.h"
 #include "llvm/ADT/SmallVector.h"
 #include <memory>
 #include <optional>
@@ -916,13 +919,31 @@
   });
 }
 
+static std::string getHeaderFilenameForStrategyKind(Strategy::Kind TargetType) {
+  switch (TargetType) {
+  case Strategy::Kind::Span:
+    return "span";
+  case Strategy::Kind::Array:
+    return "array";
+  case Strategy::Kind::Vector:
+    return "vector";
+  case Strategy::Kind::Iterator:
+    return "span";
+  case Strategy::Kind::Wontfix:
+    assert(false && "Wonfix strategy shouldn't be used to generate Fix-Its");
+  };
+}
+
 static std::map<const VarDecl *, FixItList>
 getFixIts(FixableGadgetSets &FixablesForUnsafeVars, const Strategy &S,
           const DeclUseTracker &Tracker, const ASTContext &Ctx,
           UnsafeBufferUsageHandler &Handler) {
+  const SourceManager &SM = Ctx.getSourceManager();
   std::map<const VarDecl *, FixItList> FixItsForVariable;
   for (const auto &[VD, Fixables] : FixablesForUnsafeVars.byVar) {
-    FixItsForVariable[VD] = fixVariable(VD, S.lookup(VD), Tracker, Ctx, Handler);
+    const Strategy::Kind ReplacementTypeForVD = S.lookup(VD);
+    FixItsForVariable[VD] =
+        fixVariable(VD, ReplacementTypeForVD, Tracker, Ctx, Handler);
     // If we fail to produce Fix-It for the declaration we have to skip the
     // variable entirely.
     if (FixItsForVariable[VD].empty()) {
@@ -942,14 +963,50 @@
                            CorrectFixes.end());
       }
     }
-    if (ImpossibleToFix)
+
+    if (ImpossibleToFix) {
       FixItsForVariable.erase(VD);
-    else
-      FixItsForVariable[VD].insert(FixItsForVariable[VD].end(),
-                                   FixItsForVD.begin(), FixItsForVD.end());
+      continue;
+    }
+
+    FixItsForVariable[VD].insert(FixItsForVariable[VD].end(),
+                                 FixItsForVD.begin(), FixItsForVD.end());
+
     // Fix-it shall not overlap with macros or/and templates:
     if (overlapWithMacro(FixItsForVariable[VD])) {
       FixItsForVariable.erase(VD);
+      continue;
+    }
+
+    assert(FixItsForVariable[VD].front().RemoveRange.isValid());
+    const FileID FileOfVarDeclFixIt =
+        SM.getFileID(FixItsForVariable[VD].front().RemoveRange.getBegin());
+
+    const FileEntry *FEOfVarDeclFixIt =
+        SM.getFileEntryForID(FileOfVarDeclFixIt);
+    if (!FEOfVarDeclFixIt) {
+      FixItsForVariable.erase(VD);
+      continue;
+    }
+    std::optional<llvm::MemoryBufferRef> FileContent =
+        SM.getBufferOrNone(FileOfVarDeclFixIt);
+    if (!FileContent) {
+      FixItsForVariable.erase(VD);
+      continue;
+    }
+
+    tooling::IncludeStyle InclStyle; // TODO set IncludeStyle
+    tooling::HeaderIncludes HeaderIncls(FEOfVarDeclFixIt->getName(),
+                                        FileContent.value().getBuffer(),
+                                        InclStyle);
+    std::optional<tooling::Replacement> Include = HeaderIncls.insert(
+        getHeaderFilenameForStrategyKind(ReplacementTypeForVD), true,
+        clang::tooling::IncludeDirective::Include);
+    if (Include.has_value()) {
+      SourceLocation HeaderInsertLoc =
+          SM.getComposedLoc(FileOfVarDeclFixIt, Include->getOffset());
+      FixItsForVariable[VD].push_back(FixItHint::CreateInsertion(
+          HeaderInsertLoc, Include->getReplacementText()));
     }
   }
   return FixItsForVariable;
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-include-header-included-file.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-include-header-included-file.cpp
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+
+// CHECK: fix-it:"{{.*}}warn-unsafe-buffer-usage-fixits-include-header.cpp":{5:1-5:1}:"#include <span>\n"
+
+// The point of this test is to make sure that if we emit Fix-Its for an included file we also add the #include directive to that file (and not necessarily the main file).
+
+#include "warn-unsafe-buffer-usage-fixits-include-header.cpp"
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-include-header.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-include-header.cpp
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+// This comment block simulate a file header comment.
+// CHECK: fix-it:"{{.*}}warn-unsafe-buffer-usage-fixits-include-header.cpp":{5:1-5:1}:"#include <span>\n"
+
+void foo() {
+  /* just some other code */
+}
+
+void local_array_subscript_simple() {
+  int tmp;
+  int *p = new int[10];
+  tmp = p[5];
+}