Index: include/clang/Basic/Diagnostic.h
===================================================================
--- include/clang/Basic/Diagnostic.h
+++ include/clang/Basic/Diagnostic.h
@@ -618,6 +618,8 @@
   /// a fatal error.
   void setSuppressAfterFatalError(bool Val) { SuppressAfterFatalError = Val; }
 
+  bool getSuppressAfterFatalError() { return SuppressAfterFatalError; }
+
   /// When set to true mask warnings that come from system headers.
   void setSuppressSystemWarnings(bool Val) {
     GetCurDiagState()->SuppressSystemWarnings = Val;
Index: include/clang/Basic/DiagnosticLexKinds.td
===================================================================
--- include/clang/Basic/DiagnosticLexKinds.td
+++ include/clang/Basic/DiagnosticLexKinds.td
@@ -399,6 +399,7 @@
 def err_pp_directive_required : Error<
   "%0 must be used within a preprocessing directive">;
 def err_pp_file_not_found : Error<"'%0' file not found">, DefaultFatal;
+def err_pp_file_not_found_keep_going : Error<"'%0' file not found">;
 def err_pp_through_header_not_found : Error<
   "'%0' required for precompiled header not found">, DefaultFatal;
 def err_pp_through_header_not_seen : Error<
Index: include/clang/Lex/PreprocessorOptions.h
===================================================================
--- include/clang/Lex/PreprocessorOptions.h
+++ include/clang/Lex/PreprocessorOptions.h
@@ -142,6 +142,12 @@
   /// compiler invocation and its buffers will be reused.
   bool RetainRemappedFileBuffers = false;
 
+  /// Whether to emit normal error instead of fatal in case the include is
+  /// missing. This should help to provide more meaningful information for the
+  /// code that uses data from the following headers which are ignored
+  /// otherwise.
+  bool KeepGoingAfterMissingInclude = false;
+
   /// The Objective-C++ ARC standard library that we should support,
   /// by providing appropriate definitions to retrofit the standard library
   /// with support for lifetime-qualified pointers.
Index: lib/Frontend/ASTUnit.cpp
===================================================================
--- lib/Frontend/ASTUnit.cpp
+++ lib/Frontend/ASTUnit.cpp
@@ -1735,6 +1735,7 @@
   PPOpts.RemappedFilesKeepOriginalName = RemappedFilesKeepOriginalName;
   PPOpts.AllowPCHWithCompilerErrors = AllowPCHWithCompilerErrors;
   PPOpts.SingleFileParseMode = SingleFileParse;
+  PPOpts.KeepGoingAfterMissingInclude = !Diags->getSuppressAfterFatalError();
 
   // Override the resources path.
   CI->getHeaderSearchOpts().ResourceDir = ResourceFilesPath;
Index: lib/Lex/PPDirectives.cpp
===================================================================
--- lib/Lex/PPDirectives.cpp
+++ lib/Lex/PPDirectives.cpp
@@ -1866,8 +1866,10 @@
 
       // If the file is still not found, just go with the vanilla diagnostic
       if (!File) {
-        Diag(FilenameTok, diag::err_pp_file_not_found) << OriginalFilename
-                                                       << FilenameRange;
+        Diag(FilenameTok, PPOpts->KeepGoingAfterMissingInclude
+                              ? diag::err_pp_file_not_found_keep_going
+                              : diag::err_pp_file_not_found)
+            << OriginalFilename << FilenameRange;
         if (IsFrameworkFound) {
           size_t SlashPos = OriginalFilename.find('/');
           assert(SlashPos != StringRef::npos &&
Index: lib/Lex/Pragma.cpp
===================================================================
--- lib/Lex/Pragma.cpp
+++ lib/Lex/Pragma.cpp
@@ -29,6 +29,7 @@
 #include "clang/Lex/ModuleLoader.h"
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Lex/PreprocessorLexer.h"
 #include "clang/Lex/Token.h"
 #include "clang/Lex/TokenLexer.h"
@@ -508,8 +509,12 @@
       LookupFile(FilenameTok.getLocation(), Filename, isAngled, nullptr,
                  nullptr, CurDir, nullptr, nullptr, nullptr, nullptr, nullptr);
   if (!File) {
-    if (!SuppressIncludeNotFoundError)
-      Diag(FilenameTok, diag::err_pp_file_not_found) << Filename;
+    if (!SuppressIncludeNotFoundError) {
+      Diag(FilenameTok, PPOpts->KeepGoingAfterMissingInclude
+                            ? diag::err_pp_file_not_found_keep_going
+                            : diag::err_pp_file_not_found)
+          << Filename;
+    }
     return;
   }