diff --git a/openmp/runtime/README.txt b/openmp/runtime/README.txt
index 6ecca7f64e88..a3cc85372f43 100644
--- a/openmp/runtime/README.txt
+++ b/openmp/runtime/README.txt
@@ -78,6 +78,7 @@ Intel(R) Many Integrated Core Architecture
               |   icc/icl     |    gcc      |   clang    |
 --------------|---------------|--------------------------|
 | Linux* OS   |   Yes(1,5)    |  Yes(2,4)   | Yes(4,6,7) |
+| FreeBSD*    |   No          |  No         | Yes(4,6,7) |
 | OS X*       |   Yes(1,3,4)  |  No         | Yes(4,6,7) |
 | Windows* OS |   Yes(1,4)    |  No         | No         |
 ----------------------------------------------------------
diff --git a/openmp/runtime/src/kmp.h b/openmp/runtime/src/kmp.h
index 777a0092ffbf..c5de3d7a12ea 100644
--- a/openmp/runtime/src/kmp.h
+++ b/openmp/runtime/src/kmp.h
@@ -88,7 +88,7 @@
 #include "kmp_lock.h"
 #include "kmp_i18n.h"
 
-#define KMP_HANDLE_SIGNALS (KMP_OS_LINUX || KMP_OS_WINDOWS || KMP_OS_DARWIN)
+#define KMP_HANDLE_SIGNALS (KMP_OS_LINUX || KMP_OS_FREEBSD || KMP_OS_WINDOWS || KMP_OS_DARWIN)
 
 #ifdef KMP_SETVERSION
 /*  from factory/Include, to get VERSION_STRING embedded for 'what'  */
@@ -460,6 +460,15 @@ typedef int PACKED_REDUCTION_METHOD_T;
  * Only Linux* OS and Windows* OS support thread affinity.
  */
 #if KMP_OS_LINUX || KMP_OS_WINDOWS
+# define KMP_AFFINITY_SUPPORTED 1
+#elif KMP_OS_DARWIN || KMP_OS_FREEBSD
+// affinity not supported
+# define KMP_AFFINITY_SUPPORTED 0
+#else
+# error "Unknown or unsupported OS"
+#endif
+
+#if KMP_AFFINITY_SUPPORTED
 
 extern size_t __kmp_affin_mask_size;
 # define KMP_AFFINITY_CAPABLE() (__kmp_affin_mask_size > 0)
@@ -719,11 +728,7 @@ extern kmp_affin_mask_t *__kmp_affinity_get_fullMask();
 # endif /* KMP_OS_LINUX */
 extern char const * __kmp_cpuinfo_file;
 
-#elif KMP_OS_DARWIN
-    // affinity not supported
-#else
-    #error "Unknown or unsupported OS"
-#endif /* KMP_OS_LINUX || KMP_OS_WINDOWS */
+#endif /* KMP_AFFINITY_SUPPORTED */
 
 #if OMP_40_ENABLED
 
@@ -944,10 +949,12 @@ extern unsigned int __kmp_place_core_offset;
 #elif KMP_OS_LINUX
 #  define KMP_INIT_WAIT  1024U          /* initial number of spin-tests   */
 #  define KMP_NEXT_WAIT   512U          /* susequent number of spin-tests */
-#elif KMP_OS_DARWIN
-/* TODO: tune for KMP_OS_DARWIN */
+#elif KMP_OS_DARWIN || KMP_OS_FREEBSD
+/* TODO: tune for OS */
 #  define KMP_INIT_WAIT  1024U          /* initial number of spin-tests   */
 #  define KMP_NEXT_WAIT   512U          /* susequent number of spin-tests */
+#else
+#  error "Unknown or unsupported OS"
 #endif
 
 #if KMP_ARCH_X86 || KMP_ARCH_X86_64
@@ -2971,7 +2978,7 @@ extern void __kmp_initialize_system_tick( void );  /* Initialize timer tick valu
 extern void __kmp_runtime_initialize( void );  /* machine specific initialization */
 extern void __kmp_runtime_destroy( void );
 
-#if KMP_OS_LINUX || KMP_OS_WINDOWS
+#if KMP_AFFINITY_SUPPORTED
 extern char *__kmp_affinity_print_mask(char *buf, int buf_len, kmp_affin_mask_t *mask);
 extern void __kmp_affinity_initialize(void);
 extern void __kmp_affinity_uninitialize(void);
@@ -2989,7 +2996,7 @@ 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( int tid, int team_size );
 
-#endif /* KMP_OS_LINUX || KMP_OS_WINDOWS */
+#endif /* KMP_AFFINITY_SUPPORTED */
 
 #if KMP_OS_LINUX && (KMP_ARCH_X86 || KMP_ARCH_X86_64 || KMP_ARCH_ARM)
 
diff --git a/openmp/runtime/src/kmp_affinity.cpp b/openmp/runtime/src/kmp_affinity.cpp
index 17baaaa0b9f7..082ec9d6c73e 100644
--- a/openmp/runtime/src/kmp_affinity.cpp
+++ b/openmp/runtime/src/kmp_affinity.cpp
@@ -21,7 +21,7 @@
 #include "kmp_str.h"
 
 
-#if KMP_OS_WINDOWS || KMP_OS_LINUX
+#if KMP_AFFINITY_SUPPORTED
 
 //
 // Print the affinity mask to the character array in a pretty format.
@@ -4543,9 +4543,4 @@ void __kmp_balanced_affinity( int tid, int nthreads )
 
 # endif /* KMP_MIC */
 
-#elif KMP_OS_DARWIN
-    // affinity not supported
-#else
-    #error "Unknown or unsupported OS"
-#endif // KMP_OS_WINDOWS || KMP_OS_LINUX
-
+#endif // KMP_AFFINITY_SUPPORTED
diff --git a/openmp/runtime/src/kmp_environment.c b/openmp/runtime/src/kmp_environment.c
index 52d3faec1872..0be9dc90c6ec 100644
--- a/openmp/runtime/src/kmp_environment.c
+++ b/openmp/runtime/src/kmp_environment.c
@@ -66,7 +66,7 @@
 #if KMP_OS_UNIX
     #include <stdlib.h>    // getenv, setenv, unsetenv.
     #include <string.h>    // strlen, strcpy.
-    #if KMP_OS_LINUX
+    #if KMP_OS_LINUX || KMP_OS_FREEBSD
         extern char * * environ;
     #elif KMP_OS_DARWIN
         #include <crt_externs.h>
diff --git a/openmp/runtime/src/kmp_ftn_entry.h b/openmp/runtime/src/kmp_ftn_entry.h
index 5dc792aee42d..8bb75d43d7ce 100644
--- a/openmp/runtime/src/kmp_ftn_entry.h
+++ b/openmp/runtime/src/kmp_ftn_entry.h
@@ -222,7 +222,7 @@ FTN_GET_LIBRARY (void)
 int FTN_STDCALL
 FTN_SET_AFFINITY( void **mask )
 {
-    #if defined(KMP_STUB) || !(KMP_OS_WINDOWS || KMP_OS_LINUX)
+    #if defined(KMP_STUB) || !KMP_AFFINITY_SUPPORTED
         return -1;
     #else
         if ( ! TCR_4(__kmp_init_middle) ) {
@@ -235,7 +235,7 @@ FTN_SET_AFFINITY( void **mask )
 int FTN_STDCALL
 FTN_GET_AFFINITY( void **mask )
 {
-    #if defined(KMP_STUB) || !(KMP_OS_WINDOWS || KMP_OS_LINUX)
+    #if defined(KMP_STUB) || !KMP_AFFINITY_SUPPORTED
         return -1;
     #else
         if ( ! TCR_4(__kmp_init_middle) ) {
@@ -248,7 +248,7 @@ FTN_GET_AFFINITY( void **mask )
 int FTN_STDCALL
 FTN_GET_AFFINITY_MAX_PROC( void )
 {
-    #if defined(KMP_STUB) || !(KMP_OS_WINDOWS || KMP_OS_LINUX)
+    #if defined(KMP_STUB) || !KMP_AFFINITY_SUPPORTED
         return 0;
     #else
         //
@@ -273,7 +273,7 @@ FTN_GET_AFFINITY_MAX_PROC( void )
 void FTN_STDCALL
 FTN_CREATE_AFFINITY_MASK( void **mask )
 {
-    #if defined(KMP_STUB) || !(KMP_OS_WINDOWS || KMP_OS_LINUX)
+    #if defined(KMP_STUB) || !KMP_AFFINITY_SUPPORTED
         *mask = NULL;
     #else
         //
@@ -290,7 +290,7 @@ FTN_CREATE_AFFINITY_MASK( void **mask )
 void FTN_STDCALL
 FTN_DESTROY_AFFINITY_MASK( void **mask )
 {
-    #if defined(KMP_STUB) || !(KMP_OS_WINDOWS || KMP_OS_LINUX)
+    #if defined(KMP_STUB) || !KMP_AFFINITY_SUPPORTED
         // Nothing
     #else
         //
@@ -312,7 +312,7 @@ FTN_DESTROY_AFFINITY_MASK( void **mask )
 int FTN_STDCALL
 FTN_SET_AFFINITY_MASK_PROC( int KMP_DEREF proc, void **mask )
 {
-    #if defined(KMP_STUB) || !(KMP_OS_WINDOWS || KMP_OS_LINUX)
+    #if defined(KMP_STUB) || !KMP_AFFINITY_SUPPORTED
         return -1;
     #else
         if ( ! TCR_4(__kmp_init_middle) ) {
@@ -325,7 +325,7 @@ FTN_SET_AFFINITY_MASK_PROC( int KMP_DEREF proc, void **mask )
 int FTN_STDCALL
 FTN_UNSET_AFFINITY_MASK_PROC( int KMP_DEREF proc, void **mask )
 {
-    #if defined(KMP_STUB) || !(KMP_OS_WINDOWS || KMP_OS_LINUX)
+    #if defined(KMP_STUB) || !KMP_AFFINITY_SUPPORTED
         return -1;
     #else
         if ( ! TCR_4(__kmp_init_middle) ) {
@@ -338,7 +338,7 @@ FTN_UNSET_AFFINITY_MASK_PROC( int KMP_DEREF proc, void **mask )
 int FTN_STDCALL
 FTN_GET_AFFINITY_MASK_PROC( int KMP_DEREF proc, void **mask )
 {
-    #if defined(KMP_STUB) || !(KMP_OS_WINDOWS || KMP_OS_LINUX)
+    #if defined(KMP_STUB) || !KMP_AFFINITY_SUPPORTED
         return -1;
     #else
         if ( ! TCR_4(__kmp_init_middle) ) {
@@ -408,7 +408,7 @@ xexpand(FTN_GET_THREAD_NUM)( void )
     #else
         int gtid;
 
-        #if KMP_OS_DARWIN
+        #if KMP_OS_DARWIN || KMP_OS_FREEBSD
             gtid = __kmp_entry_gtid();
         #elif KMP_OS_WINDOWS
             if (!__kmp_init_parallel ||
diff --git a/openmp/runtime/src/kmp_i18n.c b/openmp/runtime/src/kmp_i18n.c
index 8a89d0a8a81a..d50102ae8398 100644
--- a/openmp/runtime/src/kmp_i18n.c
+++ b/openmp/runtime/src/kmp_i18n.c
@@ -815,7 +815,7 @@ sys_error(
                 // not issue warning if strerror_r() returns `int' instead of expected `char *'.
             message = __kmp_str_format( "%s", err_msg );
 
-        #else // OS X*
+        #else // OS X*, FreeBSD etc.
 
             // XSI version of strerror_r.
 
diff --git a/openmp/runtime/src/kmp_os.h b/openmp/runtime/src/kmp_os.h
index f16760523400..bb5e72f635c8 100644
--- a/openmp/runtime/src/kmp_os.h
+++ b/openmp/runtime/src/kmp_os.h
@@ -63,9 +63,10 @@
 /* ---------------------- Operating system recognition ------------------- */
 
 #define KMP_OS_LINUX    0
+#define KMP_OS_FREEBSD  0
 #define KMP_OS_DARWIN   0
 #define KMP_OS_WINDOWS    0
-#define KMP_OS_UNIX     0  /* disjunction of KMP_OS_LINUX with KMP_OS_DARWIN */
+#define KMP_OS_UNIX     0  /* disjunction of KMP_OS_LINUX, KMP_OS_DARWIN etc. */
 
 #define KMP_ARCH_X86        0
 #define KMP_ARCH_X86_64	    0
@@ -85,11 +86,16 @@
 # define KMP_OS_LINUX 1
 #endif
 
-#if (1 != KMP_OS_LINUX + KMP_OS_DARWIN + KMP_OS_WINDOWS)
+#if ( defined __FreeBSD__ )
+# undef KMP_OS_FREEBSD
+# define KMP_OS_FREEBSD 1
+#endif
+
+#if (1 != KMP_OS_LINUX + KMP_OS_FREEBSD + KMP_OS_DARWIN + KMP_OS_WINDOWS)
 # error Unknown OS
 #endif
 
-#if KMP_OS_LINUX || KMP_OS_DARWIN
+#if KMP_OS_LINUX || KMP_OS_FREEBSD || KMP_OS_DARWIN
 # undef KMP_OS_UNIX
 # define KMP_OS_UNIX 1
 #endif
@@ -498,7 +504,7 @@ extern kmp_real64 __kmp_xchg_real64( volatile kmp_real64 *p, kmp_real64 v );
 # define KMP_XCHG_REAL64(p, v)                  __kmp_xchg_real64( (p), (v) );
 
 
-#elif (KMP_ASM_INTRINS && (KMP_OS_LINUX || KMP_OS_DARWIN)) || !(KMP_ARCH_X86 || KMP_ARCH_X86_64)
+#elif (KMP_ASM_INTRINS && (KMP_OS_LINUX || KMP_OS_FREEBSD || KMP_OS_DARWIN)) || !(KMP_ARCH_X86 || KMP_ARCH_X86_64)
 
 /* cast p to correct type so that proper intrinsic will be used */
 # define KMP_TEST_THEN_INC32(p)                 __sync_fetch_and_add( (kmp_int32 *)(p), 1 )
@@ -780,7 +786,7 @@ typedef void    (*microtask_t)( int *gtid, int *npr, ... );
 // Warning levels
 enum kmp_warnings_level {
     kmp_warnings_off = 0,		/* No warnings */
-    kmp_warnings_low,			/* Minimal warmings (default) */
+    kmp_warnings_low,			/* Minimal warnings (default) */
     kmp_warnings_explicit = 6,		/* Explicitly set to ON - more warnings */
     kmp_warnings_verbose		/* reserved */
 };
diff --git a/openmp/runtime/src/kmp_runtime.c b/openmp/runtime/src/kmp_runtime.c
index 729d66b316c4..a56e59b54fa7 100644
--- a/openmp/runtime/src/kmp_runtime.c
+++ b/openmp/runtime/src/kmp_runtime.c
@@ -4558,11 +4558,11 @@ __kmp_register_root( int initial_thread )
     KMP_DEBUG_ASSERT( root->r.r_hot_team->t.t_bar[ bs_forkjoin_barrier ].b_arrived == KMP_INIT_BARRIER_STATE );
 
 
-#if KMP_OS_WINDOWS || KMP_OS_LINUX
+#if KMP_AFFINITY_SUPPORTED
     if ( TCR_4(__kmp_init_middle) ) {
         __kmp_affinity_set_init_mask( gtid, TRUE );
     }
-#endif /* KMP_OS_WINDOWS || KMP_OS_LINUX */
+#endif /* KMP_AFFINITY_SUPPORTED */
 
     __kmp_root_counter ++;
 
@@ -8150,9 +8150,9 @@ __kmp_cleanup( void )
     }
 
     if (TCR_4(__kmp_init_middle)) {
-#if KMP_OS_WINDOWS || KMP_OS_LINUX
+#if KMP_AFFINITY_SUPPORTED
         __kmp_affinity_uninitialize();
-#endif /* KMP_OS_WINDOWS || KMP_OS_LINUX */
+#endif /* KMP_AFFINITY_SUPPORTED */
         TCW_4(__kmp_init_middle, FALSE);
     }
 
@@ -8452,7 +8452,7 @@ __kmp_determine_reduction_method( ident_t *loc, kmp_int32 global_tid,
 
         #if KMP_ARCH_X86_64
 
-            #if KMP_OS_LINUX || KMP_OS_WINDOWS || KMP_OS_DARWIN
+            #if KMP_OS_LINUX || KMP_OS_FREEBSD || KMP_OS_WINDOWS || KMP_OS_DARWIN
                 #if KMP_MIC
                     #define REDUCTION_TEAMSIZE_CUTOFF 8
                 #else // KMP_MIC
@@ -8471,7 +8471,7 @@ __kmp_determine_reduction_method( ident_t *loc, kmp_int32 global_tid,
                 }
             #else
                 #error "Unknown or unsupported OS"
-            #endif // KMP_OS_LINUX || KMP_OS_WINDOWS || KMP_OS_DARWIN
+            #endif // KMP_OS_LINUX || KMP_OS_FREEBSD || KMP_OS_WINDOWS || KMP_OS_DARWIN
 
         #elif KMP_ARCH_X86 || KMP_ARCH_ARM
 
diff --git a/openmp/runtime/src/kmp_settings.c b/openmp/runtime/src/kmp_settings.c
index 6292d55acde6..24cd4eafff77 100644
--- a/openmp/runtime/src/kmp_settings.c
+++ b/openmp/runtime/src/kmp_settings.c
@@ -1579,7 +1579,7 @@ __kmp_stg_parse_cpuinfo_file( char const * name, char const * value, void * data
     #if KMP_OS_LINUX || KMP_OS_WINDOWS
         __kmp_stg_parse_str( name, value, & __kmp_cpuinfo_file );
         K_DIAG( 1, ( "__kmp_cpuinfo_file == %s\n", __kmp_cpuinfo_file ) );
-    #elif KMP_OS_DARWIN
+    #elif !KMP_AFFINITY_SUPPORTED
         // affinity not supported
     #else
         #error "Unknown or unsupported OS"
@@ -3068,7 +3068,7 @@ __kmp_stg_print_topology_method( kmp_str_buf_t * buffer, char const * name,
 # endif /* KMP_DEBUG */
 } // __kmp_stg_print_topology_method
 
-#elif KMP_OS_DARWIN
+#elif !KMP_AFFINITY_SUPPORTED
     // affinity not supported
 #else
     #error "Unknown or unsupported OS"
@@ -4429,7 +4429,7 @@ static kmp_setting_t __kmp_stg_table[] = {
 
     { "KMP_TOPOLOGY_METHOD",               __kmp_stg_parse_topology_method,    __kmp_stg_print_topology_method,    NULL, 0, 0 },
 
-#elif KMP_OS_DARWIN
+#elif !KMP_AFFINITY_SUPPORTED
 
     //
     // KMP_AFFINITY is not supported on OS X*, nor is OMP_PLACES.
@@ -4686,7 +4686,7 @@ __kmp_stg_init( void
             rivals[ i ++ ] = NULL;
         }
 
-#elif KMP_OS_DARWIN
+#elif !KMP_AFFINITY_SUPPORTED
     // KMP_AFFINITY not supported, so OMP_PROC_BIND has no rivals.
     // OMP_PLACES not supported yet.
 #else
@@ -4768,7 +4768,7 @@ __kmp_stg_check_rivals(          // 0 -- Ok, 1 -- errors found.
     for ( ; strcmp( rivals[ i ]->name, name ) != 0; i++ ) {
         KMP_DEBUG_ASSERT( rivals[ i ] != NULL );
 
-#if KMP_OS_LINUX || KMP_OS_WINDOWS
+#if KMP_AFFINITY_SUPPORTED
         if ( rivals[ i ] == __kmp_affinity_notype ) {
             //
             // If KMP_AFFINITY is specified without a type name,
@@ -4885,7 +4885,7 @@ __kmp_env_initialize( char const * string ) {
         __kmp_stg_parse( name, value );
     }; // if
 
-#if KMP_OS_LINUX || KMP_OS_WINDOWS
+#if KMP_AFFINITY_SUPPORTED
     //
     // Special case. KMP_AFFINITY is not a rival to other affinity env vars
     // if no affinity type is specified.  We want to allow
@@ -4928,7 +4928,7 @@ __kmp_env_initialize( char const * string ) {
         }
 # undef FIND
     }
-#endif /* KMP_OS_LINUX || KMP_OS_WINDOWS */
+#endif /* KMP_AFFINITY_SUPPORTED */
 
 #if OMP_40_ENABLED
     //
@@ -4967,7 +4967,7 @@ __kmp_env_initialize( char const * string ) {
         KMP_DEBUG_ASSERT( __kmp_user_lock_kind != lk_default );
     }
 
-#if KMP_OS_LINUX || KMP_OS_WINDOWS
+#if KMP_AFFINITY_SUPPORTED
     if ( ! TCR_4(__kmp_init_middle) ) {
         //
         // Determine if the machine/OS is actually capable of supporting
@@ -4999,10 +4999,10 @@ __kmp_env_initialize( char const * string ) {
         }
         else if ( __kmp_nested_proc_bind.bind_types[0] == proc_bind_default ) {
             //
-            // On Windows* OS & Linux* OS, the default is to use the KMP_AFFINITY
-            // mechanism.  On OS X*, it is none.
+            // Where supported the default is to use the KMP_AFFINITY
+            // mechanism.  On OS X* etc. it is none.
             //
-#  if KMP_OS_WINDOWS || KMP_OS_LINUX
+#  if KMP_AFFINITY_SUPPORTED
             __kmp_nested_proc_bind.bind_types[0] = proc_bind_intel;
 #  else
             __kmp_nested_proc_bind.bind_types[0] = proc_bind_false;
@@ -5136,11 +5136,7 @@ __kmp_env_initialize( char const * string ) {
 # endif
     }
 
-#elif KMP_OS_DARWIN
-    // affinity not supported
-#else
-    #error "Unknown or unsupported OS"
-#endif /* KMP_OS_LINUX || KMP_OS_WINDOWS */
+#endif /* KMP_AFFINITY_SUPPORTED */
 
     if ( __kmp_version ) {
         __kmp_print_version_1();
diff --git a/openmp/runtime/src/kmp_version.c b/openmp/runtime/src/kmp_version.c
index 5d0de7716c05..f64d05266b82 100644
--- a/openmp/runtime/src/kmp_version.c
+++ b/openmp/runtime/src/kmp_version.c
@@ -169,7 +169,7 @@ __kmp_print_version_1( void )
             & buffer,
             "%sthread affinity support: %s\n",
             KMP_VERSION_PREF_STR,
-            #if KMP_OS_WINDOWS || KMP_OS_LINUX
+            #if KMP_AFFINITY_SUPPORTED
                 (
                     KMP_AFFINITY_CAPABLE()
                     ?
diff --git a/openmp/runtime/src/kmp_wrapper_malloc.h b/openmp/runtime/src/kmp_wrapper_malloc.h
index 431b8bcc9515..b2e3dbf9e903 100644
--- a/openmp/runtime/src/kmp_wrapper_malloc.h
+++ b/openmp/runtime/src/kmp_wrapper_malloc.h
@@ -105,6 +105,8 @@
 #if KMP_OS_WINDOWS
     #include <malloc.h>        // Windows* OS: _alloca() declared in "malloc.h".
     #define alloca _alloca     // Allow to use alloca() with no underscore.
+#elif KMP_OS_FREEBSD
+    // Declared in "stdlib.h".
 #elif KMP_OS_UNIX
     #include <alloca.h>        // Linux* OS and OS X*: alloc() declared in "alloca".
 #else
diff --git a/openmp/runtime/src/makefile.mk b/openmp/runtime/src/makefile.mk
index 80af00041fbc..9be8799cde45 100644
--- a/openmp/runtime/src/makefile.mk
+++ b/openmp/runtime/src/makefile.mk
@@ -355,10 +355,14 @@ ifeq "$(os)" "lin"
         # to remove dependency on libgcc_s:
         ifeq "$(c)" "gcc"
             ld-flags-dll += -static-libgcc
-            ld-flags-extra += -Wl,-ldl
+            ifneq "$(omp_os)" "freebsd"
+                ld-flags-extra += -Wl,-ldl
+            endif
         endif
         ifeq "$(c)" "clang"
-            ld-flags-extra += -Wl,-ldl
+            ifneq "$(omp_os)" "freebsd"
+                ld-flags-extra += -Wl,-ldl
+            endif
         endif
         ifeq "$(arch)" "32"
             ifeq "$(filter gcc clang,$(c))" ""
@@ -1247,7 +1251,7 @@ ifneq "$(os)" "lrb"
         # On Linux* OS and OS X* the test is good enough because GNU compiler knows nothing
         # about libirc and Intel compiler private lib directories, but we will grep verbose linker
         # output just in case.
-        tt-c        = gcc
+        tt-c        = cc
         ifeq "$(os)" "lin"    # GCC on OS X* does not recognize -pthread.
             tt-c-flags  += -pthread
         endif
@@ -1261,12 +1265,12 @@ ifneq "$(os)" "lrb"
             # Explicitly add dl library to avoid failure.
             tt-ld-flags += -ldl
         endif
-        ifeq "$(os)" "lin"
-            tt-ld-flags-v += -Wl,--verbose
-            tt-env        += LD_LIBRARY_PATH=".:$(LD_LIBRARY_PATH)"
-        else # mac
+        ifeq "$(os)" "mac"
             tt-ld-flags-v += -Wl,-t
             tt-env        += DYLD_LIBRARY_PATH=".:$(DYLD_LIBRARY_PATH)"
+        else # lin
+            tt-ld-flags-v += -Wl,--verbose
+            tt-env        += LD_LIBRARY_PATH=".:$(LD_LIBRARY_PATH)"
         endif
     endif
     tt-c-flags += $(tt-c-flags-rt)
@@ -1430,6 +1434,12 @@ ifneq "$(filter %-dyna win-%,$(os)-$(LINK_TYPE))" ""
             td_exp += uuid
         endif
     endif
+    ifeq "$(omp_os)" "freebsd"
+        td_exp =
+        td_exp += libc.so.7
+        td_exp += libthr.so.3
+        td_exp += libunwind.so.5
+    endif
 
     test-deps/.test : $(lib_file) $(tools_dir)check-depends.pl test-deps/.dir .rebuild
 	    $(target)
diff --git a/openmp/runtime/src/z_Linux_util.c b/openmp/runtime/src/z_Linux_util.c
index 40a539fe2e4a..664fdeafd429 100644
--- a/openmp/runtime/src/z_Linux_util.c
+++ b/openmp/runtime/src/z_Linux_util.c
@@ -22,7 +22,9 @@
 #include "kmp_i18n.h"
 #include "kmp_io.h"
 
-#include <alloca.h>
+#if !KMP_OS_FREEBSD
+# include <alloca.h>
+#endif
 #include <unistd.h>
 #include <math.h>               // HUGE_VAL.
 #include <sys/time.h>
@@ -48,6 +50,9 @@
 #elif KMP_OS_DARWIN
 # include <sys/sysctl.h>
 # include <mach/mach.h>
+#elif KMP_OS_FREEBSD
+# include <sys/sysctl.h>
+# include <pthread_np.h>
 #endif
 
 
@@ -596,7 +601,7 @@ static kmp_int32
 __kmp_set_stack_info( int gtid, kmp_info_t *th )
 {
     int            stack_data;
-#if KMP_OS_LINUX
+#if KMP_OS_LINUX || KMP_OS_FREEBSD
     /* Linux* OS only -- no pthread_getattr_np support on OS X* */
     pthread_attr_t attr;
     int            status;
@@ -611,8 +616,13 @@ __kmp_set_stack_info( int gtid, kmp_info_t *th )
         /* Fetch the real thread attributes */
         status = pthread_attr_init( &attr );
         KMP_CHECK_SYSFAIL( "pthread_attr_init", status );
+#if KMP_OS_FREEBSD
+        status = pthread_attr_get_np( pthread_self(), &attr );
+        KMP_CHECK_SYSFAIL( "pthread_attr_get_np", status );
+#else
         status = pthread_getattr_np( pthread_self(), &attr );
         KMP_CHECK_SYSFAIL( "pthread_getattr_np", status );
+#endif
         status = pthread_attr_getstack( &attr, &addr, &size );
         KMP_CHECK_SYSFAIL( "pthread_attr_getstack", status );
         KA_TRACE( 60, ( "__kmp_set_stack_info: T#%d pthread_attr_getstack returned size: %lu, "
@@ -629,16 +639,14 @@ __kmp_set_stack_info( int gtid, kmp_info_t *th )
         TCW_PTR(th->th.th_info.ds.ds_stacksize, size);
         TCW_4(th->th.th_info.ds.ds_stackgrow, FALSE);
         return TRUE;
-    } else {
-#endif /* KMP_OS_LINUX */
-        /* Use incremental refinement starting from initial conservative estimate */
-        TCW_PTR(th->th.th_info.ds.ds_stacksize, 0);
-        TCW_PTR(th -> th.th_info.ds.ds_stackbase, &stack_data);
-        TCW_4(th->th.th_info.ds.ds_stackgrow, TRUE);
-        return FALSE;
-#if KMP_OS_LINUX
     }
-#endif /* KMP_OS_LINUX */
+#endif /* KMP_OS_LINUX || KMP_OS_FREEBSD */
+
+    /* Use incremental refinement starting from initial conservative estimate */
+    TCW_PTR(th->th.th_info.ds.ds_stacksize, 0);
+    TCW_PTR(th -> th.th_info.ds.ds_stackbase, &stack_data);
+    TCW_4(th->th.th_info.ds.ds_stackgrow, TRUE);
+    return FALSE;
 }
 
 static void*
@@ -663,12 +671,8 @@ __kmp_launch_worker( void *thr )
     __kmp_itt_thread_name( gtid );
 #endif /* USE_ITT_BUILD */
 
-#if KMP_OS_LINUX
+#if KMP_AFFINITY_SUPPORTED
     __kmp_affinity_set_init_mask( gtid, FALSE );
-#elif KMP_OS_DARWIN
-    // affinity not supported
-#else
-    #error "Unknown or unsupported OS"
 #endif
 
 #ifdef KMP_CANCEL_THREADS
@@ -696,7 +700,7 @@ __kmp_launch_worker( void *thr )
     KMP_CHECK_SYSFAIL( "pthread_sigmask", status );
 #endif /* KMP_BLOCK_SIGNALS */
 
-#if KMP_OS_LINUX
+#if KMP_OS_LINUX || KMP_OS_FREEBSD
     if ( __kmp_stkoffset > 0 && gtid > 0 ) {
         padding = alloca( gtid * __kmp_stkoffset );
     }
@@ -2000,6 +2004,16 @@ __kmp_get_xproc( void ) {
             KMP_INFORM( AssumedNumCPU );
         }; // if
 
+    #elif KMP_OS_FREEBSD
+
+        int mib[] = { CTL_HW, HW_NCPU };
+        size_t len = sizeof( r );
+        if ( sysctl( mib, 2, &r, &len, NULL, 0 ) < 0 ) {
+            r = 0;
+            KMP_WARNING( CantGetNumAvailCPU );
+            KMP_INFORM( AssumedNumCPU );
+        }
+
     #else
 
         #error "Unknown or unsupported OS."
@@ -2121,12 +2135,8 @@ __kmp_runtime_destroy( void )
     if ( status != 0 && status != EBUSY ) {
         KMP_SYSFAIL( "pthread_cond_destroy", status );
     }
-    #if KMP_OS_LINUX
+    #if KMP_AFFINITY_SUPPORTED
         __kmp_affinity_uninitialize();
-    #elif KMP_OS_DARWIN
-        // affinity not supported
-    #else
-        #error "Unknown or unsupported OS"
     #endif
 
     __kmp_init_runtime = FALSE;
@@ -2243,6 +2253,11 @@ __kmp_is_address_mapped( void * addr ) {
             found = 1;
         }; // if
 
+    #elif KMP_OS_FREEBSD
+
+        // FIXME(FreeBSD): Implement this.
+        found = 1;
+
     #else
 
         #error "Unknown or unsupported OS"
diff --git a/openmp/runtime/tools/common.inc b/openmp/runtime/tools/common.inc
index 8eceb98e9b02..db13251672db 100644
--- a/openmp/runtime/tools/common.inc
+++ b/openmp/runtime/tools/common.inc
@@ -26,6 +26,9 @@ ifndef omp_os
   ifeq ($(OS), Linux)
     export omp_os=linux
   endif
+  ifeq ($(OS), FreeBSD)
+    export omp_os=freebsd
+  endif
   ifeq ($(OS), Darwin)
     export omp_os=macos
   endif
diff --git a/openmp/runtime/tools/freebsd.inc b/openmp/runtime/tools/freebsd.inc
new file mode 100644
index 000000000000..add7fe9d46da
--- /dev/null
+++ b/openmp/runtime/tools/freebsd.inc
@@ -0,0 +1,13 @@
+#
+#//===----------------------------------------------------------------------===//
+#//
+#//                     The LLVM Compiler Infrastructure
+#//
+#// This file is dual licensed under the MIT and the University of Illinois Open
+#// Source Licenses. See LICENSE.txt for details.
+#//
+#//===----------------------------------------------------------------------===//
+#
+
+include tools/linux.inc
+
diff --git a/openmp/runtime/tools/lib/Platform.pm b/openmp/runtime/tools/lib/Platform.pm
index d723174a29e9..5b399f738662 100644
--- a/openmp/runtime/tools/lib/Platform.pm
+++ b/openmp/runtime/tools/lib/Platform.pm
@@ -170,6 +170,9 @@ sub target_options() {
     if ( 0 ) {
     } elsif ( $operating_system eq "GNU/Linux" ) {
         $_host_os = "lin";
+    } elsif ( $operating_system eq "FreeBSD" ) {
+        # Host OS resembles Linux.
+        $_host_os = "lin";
     } elsif ( $operating_system eq "Darwin" ) {
         $_host_os = "mac";
     } elsif ( $operating_system eq "MS Windows" ) {
diff --git a/openmp/runtime/tools/lib/Uname.pm b/openmp/runtime/tools/lib/Uname.pm
index 4eb6991f2731..e212501e6dbe 100644
--- a/openmp/runtime/tools/lib/Uname.pm
+++ b/openmp/runtime/tools/lib/Uname.pm
@@ -139,11 +139,11 @@ $values{ processor } = $values{ machine };
 
 # hardware_platform.
 if ( 0 ) {
-} elsif ( $^O eq "linux" ) {
+} elsif ( $^O eq "linux" or $^O eq "freebsd" ) {
     if ( 0 ) {
     } elsif ( $values{ machine } =~ m{\Ai[3456]86\z} ) {
         $values{ hardware_platform } = "i386";
-    } elsif ( $values{ machine } =~ m{\Ax86_64\z} ) {
+    } elsif ( $values{ machine } =~ m{\A(x86_64|amd64)\z} ) {
         $values{ hardware_platform } = "x86_64";
     } elsif ( $values{ machine } =~ m{\Aarmv7\D*\z} ) {
         $values{ hardware_platform } = "arm";
@@ -370,8 +370,10 @@ if ( 0 ) {
     # $values{ operating_system_update  } = $os_name[ 1 ];
 } elsif ( $values{ kernel_name } =~ m{\ACYGWIN_NT-} ) {
     $values{ operating_system } = "MS Windows";
+} elsif ( $values{ kernel_name } =~ m{\AFreeBSD} ) {
+    $values{ operating_system } = "FreeBSD";
 } else {
-    die "Unsuppoprted kernel_name (\"$values{ kernel_name }\") returned by POSIX::uname(); stopped";
+    die "Unsupported kernel_name (\"$values{ kernel_name }\") returned by POSIX::uname(); stopped";
 }; # if
 
 # host_name and domain_name