diff --git a/openmp/runtime/src/kmp_affinity.cpp b/openmp/runtime/src/kmp_affinity.cpp
diff --git a/openmp/runtime/src/kmp_affinity.h b/openmp/runtime/src/kmp_affinity.h
@@ -57,6 +57,13 @@ class Address {
     bool operator!=(const Address &b) const {
         return !operator==(b);
     }
+    void print() const {
+        unsigned i;
+        printf("Depth: %u --- ", depth);
+        for(i=0;i<depth;i++) {
+            printf("%u ", labels[i]);
+        }
+    }
 };
 
 class AddrUnsPair {
@@ -72,6 +79,18 @@ class AddrUnsPair {
         second = b.second;
         return *this;
     }
+    void print() const {
+        printf("first = "); first.print();
+        printf(" --- second = %u", second);
+    }
+    bool operator==(const AddrUnsPair &b) const {
+        if(first != b.first) return false;
+        if(second != b.second) return false;
+        return true;
+    }
+    bool operator!=(const AddrUnsPair &b) const {
+        return !operator==(b);
+    }
 };
 
 

diff --git a/openmp/runtime/src/kmp_config.h.cmake b/openmp/runtime/src/kmp_config.h.cmake
@@ -51,6 +51,8 @@
 #cmakedefine01 LIBOMP_ENABLE_ASSERTIONS
 #define KMP_USE_ASSERT LIBOMP_ENABLE_ASSERTIONS
 #cmakedefine01 STUBS_LIBRARY
+#cmakedefine01 LIBOMP_USE_HWLOC
+#define KMP_USE_HWLOC LIBOMP_USE_HWLOC
 #define KMP_ARCH_STR "@LIBOMP_LEGAL_ARCH@"
 #define KMP_LIBRARY_FILE "@LIBOMP_LIB_FILE@"
 #define KMP_VERSION_MAJOR @LIBOMP_VERSION_MAJOR@

diff --git a/openmp/runtime/src/kmp_ftn_entry.h b/openmp/runtime/src/kmp_ftn_entry.h
@@ -257,7 +257,7 @@ FTN_GET_AFFINITY_MAX_PROC( void )
             return 0;
         }
 
-    #if KMP_GROUP_AFFINITY
+    #if KMP_GROUP_AFFINITY && !KMP_USE_HWLOC
         if ( __kmp_num_proc_groups > 1 ) {
             return (int)KMP_CPU_SETSIZE;
         }
@@ -278,7 +278,11 @@ FTN_CREATE_AFFINITY_MASK( void **mask )
         if ( ! TCR_4(__kmp_init_middle) ) {
             __kmp_middle_initialize();
         }
+    # if KMP_USE_HWLOC
+        *mask = (hwloc_cpuset_t)hwloc_bitmap_alloc();
+    # else
         *mask = kmpc_malloc( __kmp_affin_mask_size );
+    # endif
         KMP_CPU_ZERO( (kmp_affin_mask_t *)(*mask) );
     #endif
 }
@@ -300,7 +304,11 @@ FTN_DESTROY_AFFINITY_MASK( void **mask )
 	        KMP_FATAL( AffinityInvalidMask, "kmp_destroy_affinity_mask" );
 	    }
         }
+    # if KMP_USE_HWLOC
+        hwloc_bitmap_free((hwloc_cpuset_t)(*mask));
+    # else
         kmpc_free( *mask );
+    # endif
         *mask = NULL;
     #endif
 }

diff --git a/openmp/runtime/src/kmp_global.c b/openmp/runtime/src/kmp_global.c
@@ -33,6 +33,10 @@ __thread kmp_stats_list* __kmp_stats_thread_ptr = &__kmp_stats_list;
 // gives reference tick for all events (considered the 0 tick)
 tsc_tick_count __kmp_stats_start_time;
 #endif
+#if KMP_USE_HWLOC
+int __kmp_hwloc_error = FALSE;
+hwloc_topology_t __kmp_hwloc_topology = NULL;
+#endif
 
 /* ----------------------------------------------------- */
 /* INITIALIZATION VARIABLES */

diff --git a/openmp/runtime/src/kmp_settings.c b/openmp/runtime/src/kmp_settings.c
@@ -3009,6 +3009,11 @@ __kmp_stg_parse_topology_method( char const * name, char const * value,
     else if ( __kmp_str_match( "flat", 1, value ) ) {
         __kmp_affinity_top_method = affinity_top_method_flat;
     }
+# if KMP_USE_HWLOC
+    else if ( __kmp_str_match( "hwloc", 1, value) ) {
+        __kmp_affinity_top_method = affinity_top_method_hwloc;
+    }
+# endif
     else {
         KMP_WARNING( StgInvalidValue, name, value );
     }
@@ -5119,11 +5124,43 @@ __kmp_env_initialize( char const * string ) {
         // affinity.
         //
         const char *var = "KMP_AFFINITY";
+# if KMP_USE_HWLOC
+        if(hwloc_topology_init(&__kmp_hwloc_topology) < 0) {
+            __kmp_hwloc_error = TRUE;
+            if(__kmp_affinity_verbose)
+                KMP_WARNING(AffHwlocErrorOccurred, var, "hwloc_topology_init()");
+        }
+        hwloc_topology_ignore_type(__kmp_hwloc_topology, HWLOC_OBJ_CACHE);
+# endif
         if ( __kmp_affinity_type == affinity_disabled ) {
             KMP_AFFINITY_DISABLE();
         }
         else if ( ! KMP_AFFINITY_CAPABLE() ) {
+# if KMP_USE_HWLOC
+            const hwloc_topology_support* topology_support = hwloc_topology_get_support(__kmp_hwloc_topology);
+            if(hwloc_topology_load(__kmp_hwloc_topology) < 0) {
+                __kmp_hwloc_error = TRUE;
+                if(__kmp_affinity_verbose)
+                    KMP_WARNING(AffHwlocErrorOccurred, var, "hwloc_topology_load()");
+            }
+            // Is the system capable of setting/getting this thread's affinity?
+            // also, is topology discovery possible? (pu indicates ability to discover processing units)
+            // and finally, were there no errors when calling any hwloc_* API functions?
+            if(topology_support->cpubind->set_thisthread_cpubind &&
+               topology_support->cpubind->get_thisthread_cpubind &&
+               topology_support->discovery->pu &&
+               !__kmp_hwloc_error)
+            {
+                // enables affinity according to KMP_AFFINITY_CAPABLE() macro
+                KMP_AFFINITY_ENABLE(TRUE);
+            } else {
+                // indicate that hwloc didn't work and disable affinity
+                __kmp_hwloc_error = TRUE;
+                KMP_AFFINITY_DISABLE();
+            }
+# else
             __kmp_affinity_determine_capable( var );
+# endif // KMP_USE_HWLOC
             if ( ! KMP_AFFINITY_CAPABLE() ) {
                 if ( __kmp_affinity_verbose || ( __kmp_affinity_warnings
                   && ( __kmp_affinity_type != affinity_default )

diff --git a/openmp/runtime/src/z_Linux_util.c b/openmp/runtime/src/z_Linux_util.c
@@ -175,8 +175,11 @@ __kmp_set_system_affinity( kmp_affin_mask_t const *mask, int abort_on_error )
 {
     KMP_ASSERT2(KMP_AFFINITY_CAPABLE(),
       "Illegal set affinity operation when not capable");
-
+#if KMP_USE_HWLOC
+    int retval = hwloc_set_cpubind(__kmp_hwloc_topology, (hwloc_cpuset_t)mask, HWLOC_CPUBIND_THREAD);
+#else
     int retval = syscall( __NR_sched_setaffinity, 0, __kmp_affin_mask_size, mask );
+#endif
     if (retval >= 0) {
         return 0;
     }
@@ -198,7 +201,11 @@ __kmp_get_system_affinity( kmp_affin_mask_t *mask, int abort_on_error )
     KMP_ASSERT2(KMP_AFFINITY_CAPABLE(),
       "Illegal get affinity operation when not capable");
 
+#if KMP_USE_HWLOC
+    int retval = hwloc_get_cpubind(__kmp_hwloc_topology, (hwloc_cpuset_t)mask, HWLOC_CPUBIND_THREAD);
+#else
     int retval = syscall( __NR_sched_getaffinity, 0, __kmp_affin_mask_size, mask );
+#endif
     if (retval >= 0) {
         return 0;
     }
@@ -220,10 +227,12 @@ __kmp_affinity_bind_thread( int which )
     KMP_ASSERT2(KMP_AFFINITY_CAPABLE(),
       "Illegal set affinity operation when not capable");
 
-    kmp_affin_mask_t *mask = (kmp_affin_mask_t *)KMP_ALLOCA(__kmp_affin_mask_size);
+    kmp_affin_mask_t *mask;
+    KMP_CPU_ALLOC_ON_STACK(mask);
     KMP_CPU_ZERO(mask);
     KMP_CPU_SET(which, mask);
     __kmp_set_system_affinity(mask, TRUE);
+    KMP_CPU_FREE_FROM_STACK(mask);
 }
 
 /*

diff --git a/openmp/runtime/test/CMakeLists.txt b/openmp/runtime/test/CMakeLists.txt
@@ -1,12 +1,23 @@
 # CMakeLists.txt file for unit testing OpenMP Library
 include(FindPythonInterp)
 include(CheckTypeSize)
+
 if(NOT PYTHONINTERP_FOUND)
   libomp_warning_say("Could not find Python.")
   libomp_warning_say("The check-libomp target will not be available!")
   return()
 endif()
 
+macro(pythonize_bool var)
+  if (${var})
+    set(${var} True)
+  else()
+    set(${var} False)
+  endif()
+endmacro()
+
+pythonize_bool(LIBOMP_USE_HWLOC)
+
 set(LIBOMP_TEST_CFLAGS "" CACHE STRING
   "Extra compiler flags to send to the test compiler")
 

diff --git a/openmp/runtime/test/lit.cfg b/openmp/runtime/test/lit.cfg
@@ -9,11 +9,20 @@ if 'PYLINT_IMPORT' in os.environ:
     config = object()
     lit_config = object()
 
-def append_dynamic_library_path(name, value, sep):
+def append_dynamic_library_path(path):
+    if config.operating_system == 'Windows':
+        name = 'PATH'
+        sep = ';'
+    elif config.operating_system == 'Darwin':
+        name = 'DYLD_LIBRARY_PATH'
+        sep = ':'
+    else:
+        name = 'LD_LIBRARY_PATH'
+        sep = ':'
     if name in config.environment:
-        config.environment[name] = value + sep + config.environment[name]
+        config.environment[name] = path + sep + config.environment[name]
     else:
-        config.environment[name] = value
+        config.environment[name] = path
 
 # name: The name of this test suite.
 config.name = 'libomp'
@@ -38,13 +47,15 @@ config.test_cflags = config.test_openmp_flag + \
     " " + config.test_extra_cflags
 
 # Setup environment to find dynamic library at runtime
-if config.operating_system == 'Windows':
-    append_dynamic_library_path('PATH', config.library_dir, ";")
-elif config.operating_system == 'Darwin':
-    append_dynamic_library_path('DYLD_LIBRARY_PATH', config.library_dir, ":")
+append_dynamic_library_path(config.library_dir)
+if config.using_hwloc:
+    append_dynamic_library_path(config.hwloc_library_dir)
+
+# Rpath modifications for Darwin
+if config.operating_system == 'Darwin':
     config.test_cflags += " -Wl,-rpath," + config.library_dir
-else: # Unices
-    append_dynamic_library_path('LD_LIBRARY_PATH', config.library_dir, ":")
+    if config.using_hwloc:
+        config.test_cflags += " -Wl,-rpath," + config.hwloc_library_dir
 
 # substitutions
 config.substitutions.append(("%libomp-compile-and-run", \

diff --git a/openmp/runtime/test/lit.site.cfg.in b/openmp/runtime/test/lit.site.cfg.in
@@ -7,6 +7,8 @@ config.libomp_obj_root = "@CMAKE_CURRENT_BINARY_DIR@"
 config.library_dir = "@LIBOMP_LIBRARY_DIR@"
 config.omp_header_directory = "@LIBOMP_BINARY_DIR@/src"
 config.operating_system = "@CMAKE_SYSTEM_NAME@"
+config.hwloc_library_dir = "@LIBOMP_HWLOC_LIBRARY_DIR@"
+config.using_hwloc = @LIBOMP_USE_HWLOC@
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@LIBOMP_BASE_DIR@/test/lit.cfg")