diff --git a/util/generate_build_files.py b/util/generate_build_files.py
index af02ed0..92bc08e 100644
--- a/util/generate_build_files.py
+++ b/util/generate_build_files.py
@@ -528,6 +528,20 @@
   endif()
 endif()
 
+# CMake's iOS support uses Apple's multiple-architecture toolchain. It takes an
+# architecture list from CMAKE_OSX_ARCHITECTURES, leaves CMAKE_SYSTEM_PROCESSOR
+# alone, and expects all architecture-specific logic to be conditioned within
+# the source files rather than the build. This does not work for our assembly
+# files, so we fix CMAKE_SYSTEM_PROCESSOR and only support single-architecture
+# builds.
+if(NOT OPENSSL_NO_ASM AND CMAKE_OSX_ARCHITECTURES)
+  list(LENGTH CMAKE_OSX_ARCHITECTURES NUM_ARCHES)
+  if(NOT ${NUM_ARCHES} EQUAL 1)
+    message(FATAL_ERROR "Universal binaries not supported.")
+  endif()
+  list(GET CMAKE_OSX_ARCHITECTURES 0 CMAKE_SYSTEM_PROCESSOR)
+endif()
+
 include_directories(src/include)
 
 '''
@@ -584,8 +598,14 @@
       self.PrintLibrary(cmake, 'crypto',
           files['crypto'] + ['${CRYPTO_ARCH_SOURCES}'])
       self.PrintLibrary(cmake, 'ssl', files['ssl'])
-      self.PrintExe(cmake, 'bssl', files['tool'],
-          ['ssl', 'crypto', '-lpthread'])
+      self.PrintExe(cmake, 'bssl', files['tool'], ['ssl', 'crypto'])
+
+      cmake.write(
+R'''if(NOT MSVC AND NOT ANDROID)
+  target_link_libraries(crypto pthread)
+endif()
+
+''')
 
 def FindCMakeFiles(directory):
   """Returns list of all CMakeLists.txt files recursively in directory."""