diff --git a/vhdlpp/std_funcs.cc b/vhdlpp/std_funcs.cc
index 93da71b82..7dab67cc7 100644
--- a/vhdlpp/std_funcs.cc
+++ b/vhdlpp/std_funcs.cc
@@ -199,6 +199,28 @@ void preload_std_funcs(void)
                                            fn_std_logic_vector_args, &primitive_STDLOGIC_VECTOR);
     register_std_subprogram(fn_std_logic_vector);
 
+    /* numeric_std library
+     * function shift_left (arg: unsigned; count: natural) return unsigned;
+     */
+    std::list<InterfacePort*>*fn_shift_left_args = new std::list<InterfacePort*>();
+    fn_shift_left_args->push_back(new InterfacePort(&primitive_UNSIGNED));
+    fn_shift_left_args->push_back(new InterfacePort(&primitive_UNSIGNED));
+    SubprogramBuiltin*fn_shift_left = new SubprogramBuiltin(perm_string::literal("shift_left"),
+                                           perm_string::literal("$ivlh_shift_left"),
+                                           fn_shift_left_args, &primitive_UNSIGNED);
+    register_std_subprogram(fn_shift_left);
+
+    /* numeric_std library
+     * function shift_right (arg: unsigned; count: natural) return unsigned;
+     */
+    std::list<InterfacePort*>*fn_shift_right_args = new std::list<InterfacePort*>();
+    fn_shift_right_args->push_back(new InterfacePort(&primitive_UNSIGNED));
+    fn_shift_right_args->push_back(new InterfacePort(&primitive_UNSIGNED));
+    SubprogramBuiltin*fn_shift_right = new SubprogramBuiltin(perm_string::literal("shift_right"),
+                                           perm_string::literal("$ivlh_shift_right"),
+                                           fn_shift_right_args, &primitive_UNSIGNED);
+    register_std_subprogram(fn_shift_right);
+
     /* function resize
      */
     fn_resize = new SubprogramSizeCast(perm_string::literal("resize"));
diff --git a/vpi/Makefile.in b/vpi/Makefile.in
index 4a5502902..aebdb70b2 100644
--- a/vpi/Makefile.in
+++ b/vpi/Makefile.in
@@ -75,7 +75,7 @@ V = va_math.o
 
 V2009 = v2009_table.o v2009_array.o v2009_enum.o v2009_string.o
 
-VHDL_SYS = vhdl_table.o
+VHDL_SYS = vhdl_table.o sys_priv.o
 
 VHDL_TEXTIO = vhdl_textio.o sys_priv.o
 
diff --git a/vpi/vhdl_sys.sft b/vpi/vhdl_sys.sft
index d0d452212..86903476f 100644
--- a/vpi/vhdl_sys.sft
+++ b/vpi/vhdl_sys.sft
@@ -1,3 +1,6 @@
 $ivlh_attribute_event	vpiSysFuncSized 1 unsigned
 $ivlh_rising_edge	vpiSysFuncSized 1 unsigned
 $ivlh_falling_edge	vpiSysFuncSized 1 unsigned
+
+$ivlh_shift_left        vpiSysFuncSized 32 unsigned
+$ivlh_shift_right       vpiSysFuncSized 32 unsigned
diff --git a/vpi/vhdl_table.c b/vpi/vhdl_table.c
index a6db9c717..64cfe0386 100644
--- a/vpi/vhdl_table.c
+++ b/vpi/vhdl_table.c
@@ -21,6 +21,7 @@
 # include  "vpi_user.h"
 # include  <assert.h>
 # include  "ivl_alloc.h"
+# include  "sys_priv.h"
 
 /*
  * The $ivlh_attribute_event implements the VHDL <varname>'event
@@ -50,6 +51,14 @@ static const char* attr_func_names[] = {
     "$ivlh_rising_edge",
     "$ivlh_falling_edge"
 };
+
+typedef enum {
+    SHIFT_LEFT      = 0,
+    SHIFT_RIGHT     = 1,
+} shift_type_t;
+static const char* shift_func_names[] = {
+    "$ivlh_shift_left",
+    "$ivlh_shift_right",
 };
 
 /* To keep valgrind happy free the allocated memory. */
@@ -185,6 +194,43 @@ static PLI_INT32 ivlh_attribute_event_sizetf(ICARUS_VPI_CONST PLI_BYTE8*type)
       return 1;
 }
 
+static PLI_INT32 ivlh_shift_calltf(ICARUS_VPI_CONST PLI_BYTE8*data)
+{
+      shift_type_t shift_type = (shift_type_t) data;
+      vpiHandle callh = vpi_handle(vpiSysTfCall, 0);
+      vpiHandle argv = vpi_iterate(vpiArgument, callh);
+      vpiHandle argh  = vpi_scan(argv);
+      vpiHandle counth = vpi_scan(argv);
+      s_vpi_value val;
+      PLI_INT32 count;
+
+      vpi_free_object(argv);
+
+      val.format = vpiIntVal;
+      vpi_get_value(counth, &val);
+      count = val.value.integer;
+
+      val.format = vpiIntVal;
+      vpi_get_value(argh, &val);
+
+      if(shift_type == SHIFT_LEFT)
+          val.value.integer <<= count;
+      else if(shift_type == SHIFT_RIGHT)
+          val.value.integer >>= count;
+      else
+          assert(0);
+
+      vpi_put_value(callh, &val, 0, vpiNoDelay);
+
+      return 0;
+}
+
+static PLI_INT32 ivlh_shift_sizetf(ICARUS_VPI_CONST PLI_BYTE8*type)
+{
+      (void) type;  /* Parameter is not used. */
+      return 32;
+}
+
 static void vhdl_register(void)
 {
       s_vpi_systf_data tf_data;
@@ -210,6 +256,22 @@ static void vhdl_register(void)
       tf_data.tfname       = attr_func_names[FALLING_EDGE];
       tf_data.user_data    = (PLI_BYTE8*) FALLING_EDGE;
       res = vpi_register_systf(&tf_data);
+      vpip_make_systf_system_defined(res);
+
+      /* Shift functions */
+      tf_data.type         = vpiSysFunc;
+      tf_data.sysfunctype  = vpiSizedFunc;
+      tf_data.calltf       = ivlh_shift_calltf;
+      tf_data.compiletf    = sys_two_numeric_args_compiletf;
+      tf_data.sizetf       = ivlh_shift_sizetf;
+      tf_data.tfname       = shift_func_names[SHIFT_LEFT];
+      tf_data.user_data    = (PLI_BYTE8*) SHIFT_LEFT;
+      res = vpi_register_systf(&tf_data);
+      vpip_make_systf_system_defined(res);
+
+      tf_data.tfname       = shift_func_names[SHIFT_RIGHT];
+      tf_data.user_data    = (PLI_BYTE8*) SHIFT_RIGHT;
+      res = vpi_register_systf(&tf_data);
       vpip_make_systf_system_defined(res);
 
 	/* Create a callback to clear the monitor data memory when the