diff --git a/iwyu_output.cc b/iwyu_output.cc
index 7d57886..cea2281 100644
--- a/iwyu_output.cc
+++ b/iwyu_output.cc
@@ -598,6 +598,10 @@ void IwyuFileInfo::ReportMacroUse(clang::SourceLocation use_loc,
   LogSymbolUse("Marked full-info use of macro", symbol_uses_.back());
 }
 
+void IwyuFileInfo::ReportDefinedMacroUse(const clang::FileEntry* used_in) {
+  macro_users_.insert(used_in);
+}
+
 void IwyuFileInfo::ReportIncludeFileUse(const clang::FileEntry* included_file,
                                         const string& quoted_include) {
   symbol_uses_.push_back(OneUse("", included_file, quoted_include,
@@ -605,7 +609,7 @@ void IwyuFileInfo::ReportIncludeFileUse(const clang::FileEntry* included_file,
   LogSymbolUse("Marked use of include-file", symbol_uses_.back());
 }
 
-void IwyuFileInfo::ReportPragmaKeep(const clang::FileEntry* included_file) {
+void IwyuFileInfo::ReportKnownDesiredFile(const FileEntry* included_file) {
   kept_includes_.insert(included_file);
 }
 
@@ -1887,6 +1891,41 @@ size_t PrintableDiffs(const string& filename,
 
 }  // namespace internal
 
+void IwyuFileInfo::HandlePreprocessingDone() {
+  // Check macros defined by includer.  Requires file preprocessing to be
+  // finished to know all direct includes and all macro usages.
+  bool should_report_violations = ShouldReportIWYUViolationsFor(file_);
+  std::list<const FileEntry*> direct_macro_use_includees;
+  std::set_intersection(macro_users_.begin(), macro_users_.end(),
+                        direct_includes_as_fileentries_.begin(),
+                        direct_includes_as_fileentries_.end(),
+                        std::inserter(direct_macro_use_includees,
+                                      direct_macro_use_includees.end()));
+  for (const FileEntry* macro_use_includee : direct_macro_use_includees) {
+    if (should_report_violations) {
+      ERRSYM(file_) << "Keep #include " << macro_use_includee->getName()
+                    << " in " << file_->getName()
+                    << " because used macro is defined by includer.\n";
+      ReportKnownDesiredFile(macro_use_includee);
+    } else {
+      string private_include =
+          ConvertToQuotedInclude(GetFilePath(macro_use_includee));
+      if (GlobalIncludePicker().IsPublic(macro_use_includee)) {
+        ERRSYM(file_) << "Skip marking " << quoted_file_
+                      << " as public header for " << private_include
+                      << " because latter is already marked as public,"
+                      << " though uses macro defined by includer.\n";
+      } else {
+        ERRSYM(file_) << "Mark " << quoted_file_
+                      << " as public header for " << private_include
+                      << " because used macro is defined by includer.\n";
+        MutableGlobalIncludePicker()->AddMapping(private_include, quoted_file_);
+        MutableGlobalIncludePicker()->MarkIncludeAsPrivate(private_include);
+      }
+    }
+  }
+}
+
 void IwyuFileInfo::ResolvePendingAnalysis() {
   // Resolve using declarations:  This handles the case where there's a using
   // declaration in the file but no code is actually using it. If that
diff --git a/iwyu_output.h b/iwyu_output.h
index a8191f8..9fdbf2f 100644
--- a/iwyu_output.h
+++ b/iwyu_output.h
@@ -235,10 +235,14 @@ class IwyuFileInfo {
                            const string& symbol);
   // TODO(dsturtevant): Can we determine in_cxx_method_body? Do we care?
 
+  // Called when using a macro in this file.
   void ReportMacroUse(clang::SourceLocation use_loc,
                       clang::SourceLocation dfn_loc,
                       const string& symbol);
 
+  // Called when somebody uses a macro defined in this file.
+  void ReportDefinedMacroUse(const clang::FileEntry* used_in);
+
   // We only allow forward-declaring of decls, not arbitrary symbols.
   void ReportForwardDeclareUse(clang::SourceLocation use_loc,
                                const clang::NamedDecl* decl,
@@ -256,15 +260,19 @@ class IwyuFileInfo {
   void ReportIncludeFileUse(const clang::FileEntry* included_file,
                             const string& quoted_include);
 
-  // This is used when we see an "IWYU pragma: keep" comment
-  // on an include line.
-  void ReportPragmaKeep(const clang::FileEntry* included_file);
+  // This is used when we see a file we want to keep not due to symbol-use
+  // reasons.  For example, it can be #included with an "IWYU pragma: keep"
+  // comment or it can be an x-macro.
+  void ReportKnownDesiredFile(const clang::FileEntry* included_file);
 
   // This is used only in iwyu_preprocessor.cc.  TODO(csilvers): revamp?
   const set<const clang::FileEntry*>& direct_includes_as_fileentries() const {
     return direct_includes_as_fileentries_;
   }
 
+  // Called when all macros in the file are processed.
+  void HandlePreprocessingDone();
+
   // Resolve and pending analysis that needs to occur between AST traversal
   // and CalculateAndReportIwyuViolations.
   void ResolvePendingAnalysis();
@@ -345,9 +353,13 @@ class IwyuFileInfo {
   set<const clang::FileEntry*> direct_includes_as_fileentries_;
   set<const clang::NamedDecl*> direct_forward_declares_;
 
-  // Holds any files included with the "IWYU pragma: keep" comment.
+  // Holds files forced to be kept.  For example, files included with the
+  // "IWYU pragma: keep" comment and x-macros.
   set<const clang::FileEntry*> kept_includes_;
 
+  // Holds files using macros defined in this file.
+  set<const clang::FileEntry*> macro_users_;
+
   // What we will recommend the #includes to be.
   set<string> desired_includes_;
   bool desired_includes_have_been_calculated_;
diff --git a/iwyu_preprocessor.cc b/iwyu_preprocessor.cc
index 71e0b01..7cb6815 100644
--- a/iwyu_preprocessor.cc
+++ b/iwyu_preprocessor.cc
@@ -11,6 +11,8 @@
 
 #include <cstddef>                      // for size_t
 #include <cstring>
+#include <algorithm>
+#include <iterator>
 #include <string>                       // for string, basic_string, etc
 #include <utility>                      // for pair, make_pair
 
@@ -47,13 +49,6 @@ using std::string;
 
 namespace SrcMgr = clang::SrcMgr;
 
-// Prints to errs() if the verbose level is at a high enough level to
-// print symbols that occur in the given file.  This is only valid
-// when used inside a class, such as IwyuAstConsumer, that defines a
-// method named ShouldPrintSymbolFromFile().
-#define ERRSYM(file_entry) \
-  if (!ShouldPrintSymbolFromFile(file_entry)) ; else ::llvm::errs()
-
 namespace include_what_you_use {
 
 namespace {
@@ -393,7 +388,7 @@ void IwyuPreprocessorInfo::MaybeProtectInclude(
   if (IncludeLineHasText(includer_loc, "// IWYU pragma: keep") ||
       IncludeLineHasText(includer_loc, "/* IWYU pragma: keep")) {
     protect_reason = "pragma_keep";
-    FileInfoFor(includer)->ReportPragmaKeep(includee);
+    FileInfoFor(includer)->ReportKnownDesiredFile(includee);
 
   } else if (IncludeLineHasText(includer_loc, "// IWYU pragma: export") ||
              IncludeLineHasText(includer_loc, "/* IWYU pragma: export") ||
@@ -640,13 +635,14 @@ void IwyuPreprocessorInfo::InclusionDirective(
 void IwyuPreprocessorInfo::FileChanged(SourceLocation loc,
                                        FileChangeReason reason,
                                        SrcMgr::CharacteristicKind file_type,
-                                       FileID exiting_from) {
+                                       FileID exiting_from_id) {
   switch (reason) {
     case EnterFile:
       FileChanged_EnterFile(loc);
       return;
     case ExitFile:
-      FileChanged_ExitToFile(loc, exiting_from);
+      FileChanged_ExitToFile(
+          loc, GlobalSourceManager()->getFileEntryForID(exiting_from_id));
       return;
     case RenameFile:
       FileChanged_RenameFile(loc);
@@ -737,12 +733,10 @@ void IwyuPreprocessorInfo::FileChanged_EnterFile(
 }
 
 // Called when done with an #included file and returning to the parent file.
-void IwyuPreprocessorInfo::FileChanged_ExitToFile(SourceLocation include_loc,
-                                                  FileID exiting_from_id) {
+void IwyuPreprocessorInfo::FileChanged_ExitToFile(
+      SourceLocation include_loc, const FileEntry* exiting_from) {
   ERRSYM(GetFileEntry(include_loc)) << "[ Exiting to  ] "
                                     << PrintableLoc(include_loc) << "\n";
-  const FileEntry* exiting_from = GlobalSourceManager()->getFileEntryForID(
-      exiting_from_id);
   if (HasOpenBeginExports(exiting_from)) {
     Warn(begin_exports_location_stack_.top(),
          "begin_exports without an end_exports");
@@ -767,27 +761,29 @@ void IwyuPreprocessorInfo::FileChanged_SystemHeaderPragma(SourceLocation loc) {
 void IwyuPreprocessorInfo::ReportMacroUse(const string& name,
                                           SourceLocation usage_location,
                                           SourceLocation dfn_location) {
-  const FileEntry* used_in = GetFileEntry(usage_location);
-
-  if (!ShouldReportIWYUViolationsFor(used_in))
-    return;             // ignore symbols used outside foo.{h,cc}
   // Don't report macro uses that aren't actually in a file somewhere.
   if (!dfn_location.isValid() || GetFilePath(dfn_location) == "<built-in>")
     return;
+  const FileEntry* used_in = GetFileEntry(usage_location);
+  if (ShouldReportIWYUViolationsFor(used_in)) {
+    // ignore symbols used outside foo.{h,cc}
 
-  // TODO(csilvers): this isn't really a symbol use -- it may be ok
-  // that the symbol isn't defined.  For instance:
-  //    foo.h: #define FOO
-  //    bar.h: #ifdef FOO ... #else ... #endif
-  //    baz.cc: #include "foo.h"
-  //            #include "bar.h"
-  //    bang.cc: #include "bar.h"
-  // We don't want to say that bar.h 'uses' FOO, and thus needs to
-  // #include foo.h -- adding that #include could break bang.cc.
-  // I think the solution is to have a 'soft' use -- don't remove it
-  // if it's there, but don't add it if it's not.  Or something.
-  GetFromFileInfoMap(used_in)->ReportMacroUse(usage_location, dfn_location,
-                                              name);
+    // TODO(csilvers): this isn't really a symbol use -- it may be ok
+    // that the symbol isn't defined.  For instance:
+    //    foo.h: #define FOO
+    //    bar.h: #ifdef FOO ... #else ... #endif
+    //    baz.cc: #include "foo.h"
+    //            #include "bar.h"
+    //    bang.cc: #include "bar.h"
+    // We don't want to say that bar.h 'uses' FOO, and thus needs to
+    // #include foo.h -- adding that #include could break bang.cc.
+    // I think the solution is to have a 'soft' use -- don't remove it
+    // if it's there, but don't add it if it's not.  Or something.
+    GetFromFileInfoMap(used_in)->ReportMacroUse(usage_location, dfn_location,
+                                                name);
+  }
+  const FileEntry* defined_in = GetFileEntry(dfn_location);
+  GetFromFileInfoMap(defined_in)->ReportDefinedMacroUse(used_in);
 }
 
 // As above, but get the definition location from macros_definition_loc_.
@@ -934,6 +930,9 @@ void IwyuPreprocessorInfo::PopulateTransitiveIncludeMap() {
 // The public API.
 
 void IwyuPreprocessorInfo::HandlePreprocessingDone() {
+  CHECK_(main_file_ && "Main file should be present");
+  FileChanged_ExitToFile(SourceLocation(), main_file_);
+
   // In some cases, macros can refer to macros in files that are
   // defined later in other files.  In those cases, we can't
   // do an iwyu check until all header files have been read.
@@ -945,6 +944,9 @@ void IwyuPreprocessorInfo::HandlePreprocessingDone() {
   }
 
   // Other post-processing steps.
+  for (auto& file_info_map_entry : iwyu_file_info_map_) {
+    file_info_map_entry.second.HandlePreprocessingDone();
+  }
   MutableGlobalIncludePicker()->FinalizeAddedIncludes();
   ProtectReexportIncludes(&iwyu_file_info_map_);
   PopulateIntendsToProvideMap();
diff --git a/iwyu_preprocessor.h b/iwyu_preprocessor.h
index 89e5d91..a0aaa2e 100644
--- a/iwyu_preprocessor.h
+++ b/iwyu_preprocessor.h
@@ -208,7 +208,7 @@ class IwyuPreprocessorInfo : public clang::PPCallbacks,
   // FileChanged is actually a multi-plexer for 4 different callbacks.
   void FileChanged_EnterFile(clang::SourceLocation file_beginning);
   void FileChanged_ExitToFile(clang::SourceLocation include_loc,
-                              clang::FileID exiting_from);
+                              const clang::FileEntry* exiting_from);
   void FileChanged_RenameFile(clang::SourceLocation new_file);
   void FileChanged_SystemHeaderPragma(clang::SourceLocation loc);
 
diff --git a/iwyu_verrs.h b/iwyu_verrs.h
index 7455f0e..27e575a 100644
--- a/iwyu_verrs.h
+++ b/iwyu_verrs.h
@@ -40,6 +40,13 @@ bool ShouldPrintSymbolFromFile(const clang::FileEntry* file);
   if (!::include_what_you_use::ShouldPrint( \
           verbose_level)) ; else ::llvm::errs()
 
+// Prints to errs() if the verbose level is at a high enough level to
+// print symbols that occur in the given file.  This is only valid
+// when used inside a class, such as IwyuAstConsumer, that defines a
+// method named ShouldPrintSymbolFromFile().
+#define ERRSYM(file_entry) \
+  if (!ShouldPrintSymbolFromFile(file_entry)) ; else ::llvm::errs()
+
 }  // namespace include_what_you_use
 
 #endif  // INCLUDE_WHAT_YOU_USE_IWYU_VERRS_H_
diff --git a/run_iwyu_tests.py b/run_iwyu_tests.py
index 1b69e2b..a4501c4 100755
--- a/run_iwyu_tests.py
+++ b/run_iwyu_tests.py
@@ -98,6 +98,8 @@ class OneIwyuTest(unittest.TestCase):
       'deleted_implicit.cc' : ['-std=c++11'],
       'lambda_fwd_decl.cc': ['-std=c++11'],
       'lateparsed_template.cc': ['-fdelayed-template-parsing'],
+      'macro_defined_by_includer.cc': [
+          '-std=c++11', '-DCOMMAND_LINE_TYPE=double'],
       'ms_inline_asm.cc': ['-fms-extensions'],
       'prefix_header_attribution.cc': [self.Include('prefix_header_attribution-d1.h')],
       'prefix_header_includes_add.cc': prefix_headers,
@@ -140,6 +142,7 @@ class OneIwyuTest(unittest.TestCase):
       'iwyu_stricter_than_cpp.cc': ['.'],
       'keep_mapping.cc': ['.'],
       'lateparsed_template.cc': ['.'],
+      'macro_defined_by_includer.cc': ['.'],
       'macro_location.cc': ['.'],
       'member_expr.cc': ['.'],
       'multiple_include_paths.cc': ['.'],
diff --git a/tests/cxx/macro_defined_by_includer-d1.h b/tests/cxx/macro_defined_by_includer-d1.h
new file mode 100644
index 0000000..b6f1ba0
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-d1.h
@@ -0,0 +1,12 @@
+//===--- macro_defined_by_includer-d1.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Header file to provide extra level of inclusion indirection.
+
+#include "tests/cxx/macro_defined_by_includer-i1.h"
diff --git a/tests/cxx/macro_defined_by_includer-d2.h b/tests/cxx/macro_defined_by_includer-d2.h
new file mode 100644
index 0000000..ca8cb53
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-d2.h
@@ -0,0 +1,15 @@
+//===--- macro_defined_by_includer-d2.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Tests case when file using macro is included from file defining macro but
+// the macro user is first encountered as include in another file.
+
+#define DIRECT_INCLUDE_GUARD_2
+#include "tests/cxx/macro_defined_by_includer-i2.h"
+#include "tests/cxx/macro_defined_by_includer-g2.h"
diff --git a/tests/cxx/macro_defined_by_includer-d3.h b/tests/cxx/macro_defined_by_includer-d3.h
new file mode 100644
index 0000000..595c0cf
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-d3.h
@@ -0,0 +1,14 @@
+//===--- macro_defined_by_includer-d3.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Tests nested guarded includes.  Covers the case when "public" mapping for
+// some private include can be in fact private.
+
+#define DIRECT_INCLUDE_GUARD_3
+#include "tests/cxx/macro_defined_by_includer-g3.h"
diff --git a/tests/cxx/macro_defined_by_includer-d4.h b/tests/cxx/macro_defined_by_includer-d4.h
new file mode 100644
index 0000000..5eab76a
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-d4.h
@@ -0,0 +1,12 @@
+//===--- macro_defined_by_includer-d4.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Header file to provide extra level of inclusion indirection.
+
+#include "tests/cxx/macro_defined_by_includer-i3.h"
diff --git a/tests/cxx/macro_defined_by_includer-g1.h b/tests/cxx/macro_defined_by_includer-g1.h
new file mode 100644
index 0000000..1e613cf
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-g1.h
@@ -0,0 +1,14 @@
+//===--- macro_defined_by_includer-g1.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DIRECT_INCLUDE_GUARD_1
+  #error Do not include directly
+#else
+  class GuardedInclude1 {};
+#endif
diff --git a/tests/cxx/macro_defined_by_includer-g2.h b/tests/cxx/macro_defined_by_includer-g2.h
new file mode 100644
index 0000000..b0d4c09
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-g2.h
@@ -0,0 +1,19 @@
+//===--- macro_defined_by_includer-g2.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef INCLUDE_WHAT_YOU_USE_TESTS_CXX_MACRO_DEFINED_BY_INCLUDER_G2_H_
+#define INCLUDE_WHAT_YOU_USE_TESTS_CXX_MACRO_DEFINED_BY_INCLUDER_G2_H_
+
+#ifndef DIRECT_INCLUDE_GUARD_2
+  #error Do not include directly
+#else
+  class GuardedInclude2 {};
+#endif
+
+#endif  // INCLUDE_WHAT_YOU_USE_TESTS_CXX_MACRO_DEFINED_BY_INCLUDER_G2_H_
diff --git a/tests/cxx/macro_defined_by_includer-g3.h b/tests/cxx/macro_defined_by_includer-g3.h
new file mode 100644
index 0000000..64eecbf
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-g3.h
@@ -0,0 +1,17 @@
+//===--- macro_defined_by_includer-g3.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#define DIRECT_INCLUDE_GUARD_4
+#include "tests/cxx/macro_defined_by_includer-g4.h"
+
+#ifndef DIRECT_INCLUDE_GUARD_3
+  #error Do not include directly
+#else
+  class GuardedInclude3 {};
+#endif
diff --git a/tests/cxx/macro_defined_by_includer-g4.h b/tests/cxx/macro_defined_by_includer-g4.h
new file mode 100644
index 0000000..b1e8b8d
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-g4.h
@@ -0,0 +1,14 @@
+//===--- macro_defined_by_includer-g4.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DIRECT_INCLUDE_GUARD_4
+  #error Do not include directly
+#else
+  class GuardedInclude4 {};
+#endif
diff --git a/tests/cxx/macro_defined_by_includer-g5.h b/tests/cxx/macro_defined_by_includer-g5.h
new file mode 100644
index 0000000..742142f
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-g5.h
@@ -0,0 +1,14 @@
+//===--- macro_defined_by_includer-g5.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DIRECT_INCLUDE_GUARD_5
+  #error Do not include directly
+#else
+  class GuardedInclude5 {};
+#endif
diff --git a/tests/cxx/macro_defined_by_includer-i1.h b/tests/cxx/macro_defined_by_includer-i1.h
new file mode 100644
index 0000000..d359441
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-i1.h
@@ -0,0 +1,11 @@
+//===--- macro_defined_by_includer-i1.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#define DIRECT_INCLUDE_GUARD_1
+#include "tests/cxx/macro_defined_by_includer-g1.h"
diff --git a/tests/cxx/macro_defined_by_includer-i2.h b/tests/cxx/macro_defined_by_includer-i2.h
new file mode 100644
index 0000000..60b4a2b
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-i2.h
@@ -0,0 +1,10 @@
+//===--- macro_defined_by_includer-i2.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "tests/cxx/macro_defined_by_includer-g2.h"
diff --git a/tests/cxx/macro_defined_by_includer-i3.h b/tests/cxx/macro_defined_by_includer-i3.h
new file mode 100644
index 0000000..b7c9b41
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-i3.h
@@ -0,0 +1,14 @@
+//===--- macro_defined_by_includer-i3.h - test input file for iwyu --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Header file to test including file that uses x-macro.
+
+#define TYPE char
+#include "tests/cxx/macro_defined_by_includer-xmacro.h"
+#undef TYPE
diff --git a/tests/cxx/macro_defined_by_includer-xmacro.h b/tests/cxx/macro_defined_by_includer-xmacro.h
new file mode 100644
index 0000000..e96a8b8
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer-xmacro.h
@@ -0,0 +1,12 @@
+//===--- macro_defined_by_includer-xmacro.h - test input file for iwyu ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// File containing X-macro templates.
+
+void f(TYPE const t) {}
diff --git a/tests/cxx/macro_defined_by_includer.cc b/tests/cxx/macro_defined_by_includer.cc
new file mode 100644
index 0000000..91ac4b9
--- /dev/null
+++ b/tests/cxx/macro_defined_by_includer.cc
@@ -0,0 +1,89 @@
+//===--- macro_defined_by_includer.cc - test input file for iwyu ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Tests a few macro patterns:
+// * internal headers guarded by macro defined in designated header;
+// * x-macros.
+//
+// Usually you include a file with a macro and use that macro.  But in these
+// macro patterns macro is defined by includer and includee doesn't know where
+// the macro comes from.
+
+
+// Test guarded includes.
+#include "tests/cxx/macro_defined_by_includer-d1.h"
+// IWYU: GuardedInclude1 is...*macro_defined_by_includer-i1.h
+GuardedInclude1 g1;
+
+#include "tests/cxx/macro_defined_by_includer-d2.h"
+GuardedInclude2 g2;
+
+#include "tests/cxx/macro_defined_by_includer-d3.h"
+GuardedInclude3 g3;
+GuardedInclude4 g4;
+
+#define DIRECT_INCLUDE_GUARD_5
+#include "tests/cxx/macro_defined_by_includer-g5.h"
+GuardedInclude5 g5;
+
+
+// Test x-macros.
+#include "tests/cxx/macro_defined_by_includer-d4.h"
+
+#define TYPE int
+#include "tests/cxx/macro_defined_by_includer-xmacro.h"
+#undef TYPE
+
+// For x-macros we keep all includes even if its content isn't used.
+#define TYPE double
+#include "tests/cxx/macro_defined_by_includer-xmacro.h"
+#undef TYPE
+
+int main() {
+  // IWYU: f is...*macro_defined_by_includer-i3.h
+  f(3);
+  // IWYU: f is...*macro_defined_by_includer-i3.h
+  f('a');
+}
+
+
+// Test macro defined on command line.  Make sure that detecting file defining
+// macro works without actual file on disk.
+COMMAND_LINE_TYPE x;
+
+
+// Clang internal <limits.h> defines LLONG_MIN and #include_next system
+// <limits.h> which on Mac OS X uses LLONG_MIN.
+//
+// Test that we don't create a mapping between those 2 <limits.h> and don't try
+// to mark system <limits.h> as private.
+#include <limits.h>
+
+
+/**** IWYU_SUMMARY
+
+tests/cxx/macro_defined_by_includer.cc should add these lines:
+#include "tests/cxx/macro_defined_by_includer-i1.h"
+#include "tests/cxx/macro_defined_by_includer-i3.h"
+
+tests/cxx/macro_defined_by_includer.cc should remove these lines:
+- #include <limits.h>  // lines XX-XX
+- #include "tests/cxx/macro_defined_by_includer-d1.h"  // lines XX-XX
+- #include "tests/cxx/macro_defined_by_includer-d4.h"  // lines XX-XX
+
+The full include-list for tests/cxx/macro_defined_by_includer.cc:
+#include "tests/cxx/macro_defined_by_includer-d2.h"  // for GuardedInclude2
+#include "tests/cxx/macro_defined_by_includer-d3.h"  // for GuardedInclude3, GuardedInclude4
+#include "tests/cxx/macro_defined_by_includer-g5.h"  // for GuardedInclude5
+#include "tests/cxx/macro_defined_by_includer-i1.h"  // for GuardedInclude1
+#include "tests/cxx/macro_defined_by_includer-i3.h"  // for f
+#include "tests/cxx/macro_defined_by_includer-xmacro.h"  // lines XX-XX
+#include "tests/cxx/macro_defined_by_includer-xmacro.h"  // lines XX-XX
+
+***** IWYU_SUMMARY */