diff --git a/build/gen.py b/build/gen.py
index fce8fb18..2927da5f 100755
--- a/build/gen.py
+++ b/build/gen.py
@@ -260,17 +260,12 @@ def WriteGNNinja(path, options, linux_sysroot):
     if options.debug:
       cflags.extend(['-O0', '-g'])
     else:
-      cflags.append('-DNDEBUG')
-      cflags.append('-O3')
-      ldflags.append('-O3')
       # Use -fdata-sections and -ffunction-sections to place each function
       # or data item into its own section so --gc-sections can eliminate any
       # unused functions and data items.
       cflags.extend(['-fdata-sections', '-ffunction-sections'])
       ldflags.extend(['-fdata-sections', '-ffunction-sections'])
       ldflags.append('-Wl,-dead_strip' if is_mac else '-Wl,--gc-sections')
-      # Omit all symbol information from the output file.
-      ldflags.append('-Wl,-S' if is_mac else '-Wl,-strip-all')
       # Enable identical code-folding.
       if options.use_icf:
         ldflags.append('-Wl,--icf=all')
@@ -279,11 +274,11 @@ def WriteGNNinja(path, options, linux_sysroot):
         '-D_FILE_OFFSET_BITS=64',
         '-D__STDC_CONSTANT_MACROS', '-D__STDC_FORMAT_MACROS',
         '-pthread',
-        '-pipe',
         '-fno-exceptions',
         '-fno-rtti',
     ])
     cflags_cc.extend(['-std=c++14', '-Wno-c++11-narrowing'])
+    ldflags.append('-pthread')
 
     if is_linux:
       if linux_sysroot:
@@ -293,15 +288,6 @@ def WriteGNNinja(path, options, linux_sysroot):
         # probably resolve this and (re-)add a way to build against libc++.
         cflags.append('--sysroot=' + linux_sysroot)
         ldflags.append('--sysroot=' + linux_sysroot)
-      cflags.append('-stdlib=libstdc++')
-      ldflags.extend(['-static-libstdc++',
-                      '-stdlib=libstdc++',
-                      '-Wl,--as-needed',
-                     ])
-      libs.extend([
-          '-lgcc_s',
-          '-lpthread',
-      ])
     elif is_mac:
       min_mac_version_flag = '-mmacosx-version-min=10.9'
       cflags.append(min_mac_version_flag)