diff --git a/runtime/src/kmp.h b/runtime/src/kmp.h
index a0b4202..23eebe6 100644
--- a/runtime/src/kmp.h
+++ b/runtime/src/kmp.h
@@ -3341,7 +3341,7 @@
 extern int __kmp_aux_unset_affinity_mask_proc(int proc, void **mask);
 extern int __kmp_aux_get_affinity_mask_proc(int proc, void **mask);
 extern void __kmp_balanced_affinity(kmp_info_t *th, int team_size);
-#if KMP_OS_LINUX
+#if KMP_OS_LINUX || KMP_OS_FREEBSD
 extern int kmp_set_thread_affinity_mask_initial(void);
 #endif
 #endif /* KMP_AFFINITY_SUPPORTED */
diff --git a/runtime/src/kmp_affinity.cpp b/runtime/src/kmp_affinity.cpp
index 372c300..4c7ed31 100644
--- a/runtime/src/kmp_affinity.cpp
+++ b/runtime/src/kmp_affinity.cpp
@@ -1968,7 +1968,7 @@
   __kmp_hier_max_units[kmp_hier_layer_e::LAYER_THREAD + 1] =
       nPackages * nCoresPerPkg * __kmp_nThreadsPerCore;
   __kmp_hier_max_units[kmp_hier_layer_e::LAYER_L1 + 1] = __kmp_ncores;
-#if KMP_ARCH_X86_64 && (KMP_OS_LINUX || KMP_OS_WINDOWS)
+#if KMP_ARCH_X86_64 && (KMP_OS_LINUX || KMP_OS_FREEBSD || KMP_OS_WINDOWS)
   if (__kmp_mic_type >= mic3)
     __kmp_hier_max_units[kmp_hier_layer_e::LAYER_L2 + 1] = __kmp_ncores / 2;
   else
@@ -1982,7 +1982,7 @@
   __kmp_hier_threads_per[kmp_hier_layer_e::LAYER_THREAD + 1] = 1;
   __kmp_hier_threads_per[kmp_hier_layer_e::LAYER_L1 + 1] =
       __kmp_nThreadsPerCore;
-#if KMP_ARCH_X86_64 && (KMP_OS_LINUX || KMP_OS_WINDOWS)
+#if KMP_ARCH_X86_64 && (KMP_OS_LINUX || KMP_OS_FREEBSD || KMP_OS_WINDOWS)
   if (__kmp_mic_type >= mic3)
     __kmp_hier_threads_per[kmp_hier_layer_e::LAYER_L2 + 1] =
         2 * __kmp_nThreadsPerCore;
diff --git a/runtime/src/kmp_affinity.h b/runtime/src/kmp_affinity.h
index c00ad36..f270bb6 100644
--- a/runtime/src/kmp_affinity.h
+++ b/runtime/src/kmp_affinity.h
@@ -160,6 +160,7 @@
 };
 #endif /* KMP_USE_HWLOC */
 
+#if KMP_OS_LINUX || KMP_OS_FREEBSD
 #if KMP_OS_LINUX
 /* On some of the older OS's that we build on, these constants aren't present
    in <asm/unistd.h> #included from <sys.syscall.h>. They must be the same on
@@ -234,6 +235,10 @@
 #endif /* __NR_sched_getaffinity */
 #error Unknown or unsupported architecture
 #endif /* KMP_ARCH_* */
+#elif KMP_OS_FREEBSD
+#include <pthread.h>
+#include <pthread_np.h>
+#endif
 class KMPNativeAffinity : public KMPAffinity {
   class Mask : public KMPAffinity::Mask {
     typedef unsigned char mask_t;
@@ -294,8 +299,13 @@
     int get_system_affinity(bool abort_on_error) override {
       KMP_ASSERT2(KMP_AFFINITY_CAPABLE(),
                   "Illegal get affinity operation when not capable");
+#if KMP_OS_LINUX
       int retval =
           syscall(__NR_sched_getaffinity, 0, __kmp_affin_mask_size, mask);
+#elif KMP_OS_FREEBSD
+      int retval =
+          pthread_getaffinity_np(pthread_self(), __kmp_affin_mask_size, reinterpret_cast<cpuset_t *>(mask));
+#endif
       if (retval >= 0) {
         return 0;
       }
@@ -308,8 +318,13 @@
     int set_system_affinity(bool abort_on_error) const override {
       KMP_ASSERT2(KMP_AFFINITY_CAPABLE(),
                   "Illegal get affinity operation when not capable");
+#if KMP_OS_LINUX
       int retval =
           syscall(__NR_sched_setaffinity, 0, __kmp_affin_mask_size, mask);
+#elif KMP_OS_FREEBSD
+      int retval =
+          pthread_setaffinity_np(pthread_self(), __kmp_affin_mask_size, reinterpret_cast<cpuset_t *>(mask));
+#endif
       if (retval >= 0) {
         return 0;
       }
@@ -347,7 +362,7 @@
   }
   api_type get_api_type() const override { return NATIVE_OS; }
 };
-#endif /* KMP_OS_LINUX */
+#endif /* KMP_OS_LINUX || KMP_OS_FREEBSD */
 
 #if KMP_OS_WINDOWS
 class KMPNativeAffinity : public KMPAffinity {
diff --git a/runtime/src/kmp_os.h b/runtime/src/kmp_os.h
index ca3af3a..cd942a9 100644
--- a/runtime/src/kmp_os.h
+++ b/runtime/src/kmp_os.h
@@ -69,7 +69,7 @@
 #error Unknown compiler
 #endif
 
-#if (KMP_OS_LINUX || KMP_OS_WINDOWS) && !KMP_OS_CNK
+#if (KMP_OS_LINUX || KMP_OS_WINDOWS || KMP_OS_FREEBSD) && !KMP_OS_CNK
 #define KMP_AFFINITY_SUPPORTED 1
 #if KMP_OS_WINDOWS && KMP_ARCH_X86_64
 #define KMP_GROUP_AFFINITY 1
diff --git a/runtime/src/kmp_runtime.cpp b/runtime/src/kmp_runtime.cpp
index 82d4c26..dd6e0ff 100644
--- a/runtime/src/kmp_runtime.cpp
+++ b/runtime/src/kmp_runtime.cpp
@@ -4493,7 +4493,7 @@
   KF_TRACE(10, ("__kmp_initialize_team: exit: team=%p\n", team));
 }
 
-#if KMP_OS_LINUX && KMP_AFFINITY_SUPPORTED
+#if (KMP_OS_LINUX || KMP_OS_FREEBSD) && KMP_AFFINITY_SUPPORTED
 /* Sets full mask for thread and returns old mask, no changes to structures. */
 static void
 __kmp_set_thread_affinity_mask_full_tmp(kmp_affin_mask_t *old_mask) {
@@ -5041,7 +5041,7 @@
       __kmp_partition_places(team);
 #endif
     } else { // team->t.t_nproc < new_nproc
-#if KMP_OS_LINUX && KMP_AFFINITY_SUPPORTED
+#if (KMP_OS_LINUX || KMP_OS_FREEBSD) && KMP_AFFINITY_SUPPORTED
       kmp_affin_mask_t *old_mask;
       if (KMP_AFFINITY_CAPABLE()) {
         KMP_CPU_ALLOC(old_mask);
@@ -5090,7 +5090,7 @@
           __kmp_reinitialize_team(team, new_icvs, NULL);
         }
 
-#if KMP_OS_LINUX && KMP_AFFINITY_SUPPORTED
+#if (KMP_OS_LINUX || KMP_OS_FREEBSD) && KMP_AFFINITY_SUPPORTED
         /* Temporarily set full mask for master thread before creation of
            workers. The reason is that workers inherit the affinity from master,
            so if a lot of workers are created on the single core quickly, they
@@ -5125,7 +5125,7 @@
           }
         }
 
-#if KMP_OS_LINUX && KMP_AFFINITY_SUPPORTED
+#if (KMP_OS_LINUX || KMP_OS_FREEBSD) && KMP_AFFINITY_SUPPORTED
         if (KMP_AFFINITY_CAPABLE()) {
           /* Restore initial master thread's affinity mask */
           __kmp_set_system_affinity(old_mask, TRUE);
diff --git a/runtime/src/z_Linux_util.cpp b/runtime/src/z_Linux_util.cpp
index 871be62..0ee1292 100644
--- a/runtime/src/z_Linux_util.cpp
+++ b/runtime/src/z_Linux_util.cpp
@@ -100,7 +100,7 @@
 }
 #endif
 
-#if (KMP_OS_LINUX && KMP_AFFINITY_SUPPORTED)
+#if ((KMP_OS_LINUX || KMP_OS_FREEBSD) && KMP_AFFINITY_SUPPORTED)
 
 /* Affinity support */
 
@@ -122,16 +122,21 @@
 void __kmp_affinity_determine_capable(const char *env_var) {
 // Check and see if the OS supports thread affinity.
 
+#if KMP_OS_LINUX
 #define KMP_CPU_SET_SIZE_LIMIT (1024 * 1024)
+#elif KMP_OS_FREEBSD
+#define KMP_CPU_SET_SIZE_LIMIT (sizeof(cpuset_t))
+#endif
 
+
+#if KMP_OS_LINUX
+  // If Linux* OS:
+  // If the syscall fails or returns a suggestion for the size,
+  // then we don't have to search for an appropriate size.
   int gCode;
   int sCode;
   unsigned char *buf;
   buf = (unsigned char *)KMP_INTERNAL_MALLOC(KMP_CPU_SET_SIZE_LIMIT);
-
-  // If Linux* OS:
-  // If the syscall fails or returns a suggestion for the size,
-  // then we don't have to search for an appropriate size.
   gCode = syscall(__NR_sched_getaffinity, 0, KMP_CPU_SET_SIZE_LIMIT, buf);
   KA_TRACE(30, ("__kmp_affinity_determine_capable: "
                 "initial getaffinity call returned %d errno = %d\n",
@@ -270,6 +275,23 @@
       }
     }
   }
+#elif KMP_OS_FREEBSD
+  int gCode;
+  unsigned char *buf;
+  buf = (unsigned char *)KMP_INTERNAL_MALLOC(KMP_CPU_SET_SIZE_LIMIT);
+  gCode = pthread_getaffinity_np(pthread_self(), KMP_CPU_SET_SIZE_LIMIT, reinterpret_cast<cpuset_t *>(buf));
+  KA_TRACE(30, ("__kmp_affinity_determine_capable: "
+                "initial getaffinity call returned %d errno = %d\n",
+                gCode, errno));
+  if (gCode == 0) {
+    KMP_AFFINITY_ENABLE(KMP_CPU_SET_SIZE_LIMIT);
+    KA_TRACE(10, ("__kmp_affinity_determine_capable: "
+                  "affinity supported (mask size %d)\n"<
+		  (int)__kmp_affin_mask_size));
+    KMP_INTERNAL_FREE(buf);
+    return;
+  }
+#endif
   // save uncaught error code
   // int error = errno;
   KMP_INTERNAL_FREE(buf);