Index: tools/gyp/pylib/gyp/generator/ninja.py
===================================================================
--- tools/gyp/pylib/gyp/generator/ninja.py	(revision 1690)
+++ tools/gyp/pylib/gyp/generator/ninja.py	(working copy)
@@ -755,9 +755,16 @@
       self.WriteVariableList(ninja_file, 'pchprefix', [self.name])
     else:
       cflags = config.get('cflags', [])
-      cflags_c = config.get('cflags_c', [])
-      cflags_cc = config.get('cflags_cc', [])
 
+      # Respect environment variables related to build, but target-specific
+      # flags can still override them.
+      cflags_c = (os.environ.get('CPPFLAGS', '').split() +
+                  os.environ.get('CFLAGS', '').split() +
+                  config.get('cflags_c', []))
+      cflags_cc = (os.environ.get('CPPFLAGS', '').split() +
+                   os.environ.get('CXXFLAGS', '').split() +
+                   config.get('cflags_cc', []))
+
     defines = config.get('defines', []) + extra_defines
     self.WriteVariableList(ninja_file, 'defines',
                            [Define(d, self.flavor) for d in defines])
@@ -932,7 +939,10 @@
       if def_file:
         implicit_deps.add(def_file)
     else:
-      ldflags = config.get('ldflags', [])
+      # Respect environment variables related to build, but target-specific
+      # flags can still override them.
+      ldflags = (os.environ.get('LDFLAGS', '').split() +
+                 config.get('ldflags', []))
       if is_executable and len(solibs):
         rpath = 'lib/'
         if self.toolset != 'target':