diff --git a/lib/System/Mutex.cpp b/lib/System/Mutex.cpp
index 33dff053315..abcf77e6751 100644
--- a/lib/System/Mutex.cpp
+++ b/lib/System/Mutex.cpp
@@ -75,7 +75,7 @@ Mutex::Mutex( bool recursive)
     errorcode = pthread_mutexattr_settype(&attr, kind);
     assert(errorcode == 0);
 
-#ifndef __FreeBSD__
+#if !defined(__FreeBSD__) && !defined(__OpenBSD__)
     // Make it a process local mutex
     errorcode = pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_PRIVATE);
 #endif
diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index 4e86c6fec0d..904101287ab 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -813,7 +813,7 @@ static void generateCompilerSpecificCode(std::ostream& Out) {
       << "extern void *__builtin_alloca(unsigned int);\n"
       << "#endif\n"
       << "#define alloca(x) __builtin_alloca(x)\n"
-      << "#elif defined(__FreeBSD__)\n"
+      << "#elif defined(__FreeBSD__) || defined(__OpenBSD__)\n"
       << "#define alloca(x) __builtin_alloca(x)\n"
       << "#elif !defined(_MSC_VER)\n"
       << "#include <alloca.h>\n"
diff --git a/lib/Target/CBackend/Writer.cpp b/lib/Target/CBackend/Writer.cpp
index 4e86c6fec0d..904101287ab 100644
--- a/lib/Target/CBackend/Writer.cpp
+++ b/lib/Target/CBackend/Writer.cpp
@@ -813,7 +813,7 @@ static void generateCompilerSpecificCode(std::ostream& Out) {
       << "extern void *__builtin_alloca(unsigned int);\n"
       << "#endif\n"
       << "#define alloca(x) __builtin_alloca(x)\n"
-      << "#elif defined(__FreeBSD__)\n"
+      << "#elif defined(__FreeBSD__) || defined(__OpenBSD__)\n"
       << "#define alloca(x) __builtin_alloca(x)\n"
       << "#elif !defined(_MSC_VER)\n"
       << "#include <alloca.h>\n"