diff --git a/tools/gn/c_include_iterator.cc b/tools/gn/c_include_iterator.cc
index 25eba9d..9e719c7 100644
--- a/tools/gn/c_include_iterator.cc
+++ b/tools/gn/c_include_iterator.cc
@@ -105,6 +105,11 @@
   return type;
 }
 
+// Returns true if this line has a "nogncheck" comment associated with it.
+bool HasNoCheckAnnotation(const base::StringPiece& line) {
+  return line.find("nogncheck") != base::StringPiece::npos;
+}
+
 }  // namespace
 
 const int CIncludeIterator::kMaxNonIncludeLines = 10;
@@ -129,7 +134,7 @@
     base::StringPiece include_contents;
     int begin_char;
     IncludeType type = ExtractInclude(line, &include_contents, &begin_char);
-    if (type == INCLUDE_USER) {
+    if (type == INCLUDE_USER && !HasNoCheckAnnotation(line)) {
       // Only count user includes for now.
       *out = include_contents;
       *location = LocationRange(
diff --git a/tools/gn/c_include_iterator_unittest.cc b/tools/gn/c_include_iterator_unittest.cc
index c5b9714..11fa991 100644
--- a/tools/gn/c_include_iterator_unittest.cc
+++ b/tools/gn/c_include_iterator_unittest.cc
@@ -29,6 +29,8 @@
   buffer.append("\n");
   buffer.append(" #include \"foo/baz.h\"\n");  // Leading whitespace
   buffer.append("#include \"la/deda.h\"\n");
+  // Line annotated with "// nogncheck"
+  buffer.append("#include \"should_be_skipped.h\"  // nogncheck\n");
   buffer.append("#import \"weird_mac_import.h\"\n");
   buffer.append("\n");
   buffer.append("void SomeCode() {\n");
@@ -52,9 +54,11 @@
   EXPECT_EQ("la/deda.h", contents);
   EXPECT_TRUE(RangeIs(range, 8, 11, 20)) << range.begin().Describe(true);
 
+  // The line annotated with "nogncheck" should be skipped.
+
   EXPECT_TRUE(iter.GetNextIncludeString(&contents, &range));
   EXPECT_EQ("weird_mac_import.h", contents);
-  EXPECT_TRUE(RangeIs(range, 9, 10, 28)) << range.begin().Describe(true);
+  EXPECT_TRUE(RangeIs(range, 10, 10, 28)) << range.begin().Describe(true);
 
   EXPECT_FALSE(iter.GetNextIncludeString(&contents, &range));
 }
diff --git a/tools/gn/docs/reference.md b/tools/gn/docs/reference.md
index c55f42e..ad3ac85 100644
--- a/tools/gn/docs/reference.md
+++ b/tools/gn/docs/reference.md
@@ -1011,6 +1011,7 @@
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          defines, include_dirs, ldflags, lib_dirs, libs
+         precompiled_header, precompiled_source
 
 ```
 
@@ -1209,6 +1210,7 @@
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          defines, include_dirs, ldflags, lib_dirs, libs
+         precompiled_header, precompiled_source
   Deps: data_deps, deps, forward_dependent_configs_from, public_deps
   Dependent configs: all_dependent_configs, public_configs
   General: check_includes, configs, data, inputs, output_name,
@@ -1920,6 +1922,7 @@
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          defines, include_dirs, ldflags, lib_dirs, libs
+         precompiled_header, precompiled_source
   Deps: data_deps, deps, forward_dependent_configs_from, public_deps
   Dependent configs: all_dependent_configs, public_configs
   General: check_includes, configs, data, inputs, output_name,
@@ -1960,6 +1963,7 @@
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          defines, include_dirs, ldflags, lib_dirs, libs
+         precompiled_header, precompiled_source
   Deps: data_deps, deps, forward_dependent_configs_from, public_deps
   Dependent configs: all_dependent_configs, public_configs
   General: check_includes, configs, data, inputs, output_name,
@@ -1983,6 +1987,7 @@
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          defines, include_dirs, ldflags, lib_dirs, libs
+         precompiled_header, precompiled_source
   Deps: data_deps, deps, forward_dependent_configs_from, public_deps
   Dependent configs: all_dependent_configs, public_configs
   General: check_includes, configs, data, inputs, output_name,
@@ -2292,6 +2297,20 @@
         Posix systems:
           output_prefix = "lib"
 
+    precompiled_header_type  [string]
+        Valid for: "cc", "cxx", "objc", "objcxx"
+
+        Type of precompiled headers. If undefined or the empty string,
+        precompiled headers will not be used for this tool. Otherwise
+        use "msvc" which is the only currently supported value.
+
+        For precompiled headers to be used for a given target, the
+        target (or a config applied to it) must also specify a
+        "precompiled_header" and, for "msvc"-style headers, a
+        "precompiled_source" value.
+
+        See "gn help precompiled_header" for more.
+
     restat  [boolean]
         Valid for: all tools (optional, defaults to false)
 
@@ -2332,6 +2351,7 @@
 ```
 
 ### **Expansions for tool variables**
+
 ```
   All paths are relative to the root build directory, which is the
   current directory for running all tools. These expansions are
@@ -3242,6 +3262,30 @@
 
 ```
 
+### **Controlling includes individually**
+
+```
+  If only certain includes are problematic, you can annotate them
+  individually rather than disabling header checking on an entire
+  target. Add the string "nogncheck" to the include line:
+
+    #include "foo/something_weird.h"  // nogncheck (bug 12345)
+
+  It is good form to include a reference to a bug (if the include is
+  improper, or some other comment expressing why the header checker
+  doesn't work for this particular case.
+
+  The most common reason to need "nogncheck" is conditional includes.
+  The header checker does not understand the preprocessor, so may flag
+  some includes as improper even if the dependencies and #defines are
+  always matched correctly:
+
+    #if defined(ENABLE_DOOM_MELON)
+    #include "doom_melon/beam_controller.h"  // nogncheck
+    #endif
+
+```
+
 ### **Example**
 
 ```
@@ -3772,6 +3816,77 @@
 
 
 ```
+## **precompiled_header**: [string] Header file to precompile.
+
+```
+  Precompiled headers will be used when a target specifies this
+  value, or a config applying to this target specifies this value.
+  In addition, the tool corresponding to the source files must also
+  specify precompiled headers (see "gn help tool"). The tool
+  will also specify what type of precompiled headers to use.
+
+  The precompiled header/source variables can be specified on a target
+  or a config, but must be the same for all configs applying to a given
+  target since a target can only have one precompiled header.
+
+```
+
+### **MSVC precompiled headers**
+
+```
+  When using MSVC-style precompiled headers, the "precompiled_header"
+  value is a string corresponding to the header. This is NOT a path
+  to a file that GN recognises, but rather the exact string that appears
+  in quotes after an #include line in source code. The compiler will
+  match this string against includes or forced includes (/FI).
+
+  MSVC also requires a source file to compile the header with. This must
+  be specified by the "precompiled_source" value. In contrast to the
+  header value, this IS a GN-style file name, and tells GN which source
+  file to compile to make the .pch file used for subsequent compiles.
+
+  If you use both C and C++ sources, the precompiled header and source
+  file will be compiled using both tools. You will want to make sure
+  to wrap C++ includes in __cplusplus #ifdefs so the file will compile
+  in C mode.
+
+  For example, if the toolchain specifies MSVC headers:
+
+    toolchain("vc_x64") {
+      ...
+      tool("cxx") {
+        precompiled_header_type = "msvc"
+        ...
+
+  You might make a config like this:
+
+    config("use_precompiled_headers") {
+      precompiled_header = "build/precompile.h"
+      precompiled_source = "//build/precompile.cc"
+
+      # Either your source files should #include "build/precompile.h"
+      # first, or you can do this to force-include the header.
+      cflags = [ "/FI$precompiled_header" ]
+    }
+
+  And then define a target that uses the config:
+
+    executable("doom_melon") {
+      configs += [ ":use_precompiled_headers" ]
+      ...
+
+
+
+```
+## **precompiled_source**: [file name] Source file to precompile.
+
+```
+  The source file that goes along with the precompiled_header when
+  using "msvc"-style precompiled headers. It will be implicitly added
+  to the sources of the target. See "gn help precompiled_header".
+
+
+```
 ## **public**: Declare public header files for a target.
 
 ```
diff --git a/tools/gn/variables.cc b/tools/gn/variables.cc
index 472554a..0f3ede7 100644
--- a/tools/gn/variables.cc
+++ b/tools/gn/variables.cc
@@ -442,6 +442,27 @@
     "  This does not affect other targets that depend on the current target,\n"
     "  it just skips checking the includes of the current target's files.\n"
     "\n"
+    "Controlling includes individually\n"
+    "\n"
+    "  If only certain includes are problematic, you can annotate them\n"
+    "  individually rather than disabling header checking on an entire\n"
+    "  target. Add the string \"nogncheck\" to the include line:\n"
+    "\n"
+    "    #include \"foo/something_weird.h\"  // nogncheck (bug 12345)\n"
+    "\n"
+    "  It is good form to include a reference to a bug (if the include is\n"
+    "  improper, or some other comment expressing why the header checker\n"
+    "  doesn't work for this particular case.\n"
+    "\n"
+    "  The most common reason to need \"nogncheck\" is conditional includes.\n"
+    "  The header checker does not understand the preprocessor, so may flag\n"
+    "  some includes as improper even if the dependencies and #defines are\n"
+    "  always matched correctly:\n"
+    "\n"
+    "    #if defined(ENABLE_DOOM_MELON)\n"
+    "    #include \"doom_melon/beam_controller.h\"  // nogncheck\n"
+    "    #endif\n"
+    "\n"
     "Example\n"
     "\n"
     "  source_set(\"busted_includes\") {\n"