diff --git a/src/intel/compiler/elk/elk_fs.h b/src/intel/compiler/elk/elk_fs.h
index a5b807e18a8..0aedb4a2e92 100644
--- a/src/intel/compiler/elk/elk_fs.h
+++ b/src/intel/compiler/elk/elk_fs.h
@@ -393,7 +393,6 @@ public:
    elk_fs_reg uw_pixel_y;
    elk_fs_reg pixel_z;
    elk_fs_reg wpos_w;
-   elk_fs_reg pixel_w;
    elk_fs_reg delta_xy[ELK_BARYCENTRIC_MODE_COUNT];
    elk_fs_reg final_gs_vertex_count;
    elk_fs_reg control_data_bits;
diff --git a/src/intel/compiler/elk/elk_fs_nir.cpp b/src/intel/compiler/elk/elk_fs_nir.cpp
index da239cda24e..721a66ead5c 100644
--- a/src/intel/compiler/elk/elk_fs_nir.cpp
+++ b/src/intel/compiler/elk/elk_fs_nir.cpp
@@ -3941,8 +3941,6 @@ fs_nir_emit_fs_intrinsic(nir_to_elk_state &ntb,
       nir_intrinsic_instr *bary_intrinsic =
          nir_instr_as_intrinsic(instr->src[0].ssa->parent_instr);
       nir_intrinsic_op bary_intrin = bary_intrinsic->intrinsic;
-      enum glsl_interp_mode interp_mode =
-         (enum glsl_interp_mode) nir_intrinsic_interp_mode(bary_intrinsic);
       elk_fs_reg dst_xy;
 
       if (bary_intrin == nir_intrinsic_load_barycentric_at_offset ||
@@ -3962,13 +3960,7 @@ fs_nir_emit_fs_intrinsic(nir_to_elk_state &ntb,
          interp.type = ELK_REGISTER_TYPE_F;
          dest.type = ELK_REGISTER_TYPE_F;
 
-         if (devinfo->ver < 6 && interp_mode == INTERP_MODE_SMOOTH) {
-            elk_fs_reg tmp = s.vgrf(glsl_float_type());
-            bld.emit(ELK_FS_OPCODE_LINTERP, tmp, dst_xy, interp);
-            bld.MUL(offset(dest, bld, i), tmp, s.pixel_w);
-         } else {
-            bld.emit(ELK_FS_OPCODE_LINTERP, offset(dest, bld, i), dst_xy, interp);
-         }
+         bld.emit(ELK_FS_OPCODE_LINTERP, offset(dest, bld, i), dst_xy, interp);
       }
       break;
    }
diff --git a/src/intel/compiler/elk/elk_fs_visitor.cpp b/src/intel/compiler/elk/elk_fs_visitor.cpp
index 79bce09e1d2..9c2d3b5ab90 100644
--- a/src/intel/compiler/elk/elk_fs_visitor.cpp
+++ b/src/intel/compiler/elk/elk_fs_visitor.cpp
@@ -146,9 +146,6 @@ elk_fs_visitor::emit_interpolation_setup_gfx4()
    this->wpos_w = vgrf(glsl_float_type());
    abld.emit(ELK_FS_OPCODE_LINTERP, wpos_w, delta_xy,
              interp_reg(abld, VARYING_SLOT_POS, 3, 0));
-   /* Compute the pixel 1/W value from wpos.w. */
-   this->pixel_w = vgrf(glsl_float_type());
-   abld.emit(ELK_SHADER_OPCODE_RCP, this->pixel_w, wpos_w);
 }
 
 /** Emits the interpolation for the varying inputs. */
@@ -278,9 +275,9 @@ elk_fs_visitor::emit_interpolation_setup_gfx6()
 
    if (wm_prog_data->uses_src_w) {
       abld = bld.annotate("compute pos.w");
-      this->pixel_w = fetch_payload_reg(abld, fs_payload().source_w_reg);
       this->wpos_w = vgrf(glsl_float_type());
-      abld.emit(ELK_SHADER_OPCODE_RCP, this->wpos_w, this->pixel_w);
+      abld.emit(ELK_SHADER_OPCODE_RCP, this->wpos_w,
+                fetch_payload_reg(abld, fs_payload().source_w_reg));
    }
 
    if (wm_key->persample_interp == ELK_SOMETIMES) {
diff --git a/src/intel/compiler/elk/elk_nir.c b/src/intel/compiler/elk/elk_nir.c
index 0642880064d..d8f1b8ca211 100644
--- a/src/intel/compiler/elk/elk_nir.c
+++ b/src/intel/compiler/elk/elk_nir.c
@@ -488,6 +488,49 @@ lower_barycentric_at_offset(nir_builder *b, nir_intrinsic_instr *intrin,
    return true;
 }
 
+static bool
+elk_nir_lower_fs_smooth_interp_gfx4_instr(nir_builder *b, nir_intrinsic_instr *intr, void *_data)
+{
+   if (intr->intrinsic != nir_intrinsic_load_deref)
+      return false;
+
+   nir_deref_instr *deref = nir_instr_as_deref(intr->src[0].ssa->parent_instr);
+   nir_variable *var = nir_deref_instr_get_variable(deref);
+
+   if (var->data.interpolation != INTERP_MODE_SMOOTH)
+      return false;
+
+   /* If we haven't computed pixel_w yet, do so now (once, at the start of the
+    * shader).  CSE could do this, but this makes things more legible and saves
+    * followup optimization.
+    */
+   nir_def **pixel_w = _data;
+   if (!*pixel_w) {
+      b->cursor = nir_before_block(nir_start_block(b->impl));
+
+      nir_def *w = nir_load_frag_coord_w(b);
+      BITSET_SET(b->shader->info.system_values_read, SYSTEM_VALUE_FRAG_COORD_W);
+      *pixel_w = nir_frcp(b, w);
+   }
+
+   b->cursor = nir_after_instr(&intr->instr);
+   nir_def *result = nir_fmul(b, &intr->def, *pixel_w);
+
+   nir_def_rewrite_uses_after(&intr->def, result, result->parent_instr);
+   return true;
+}
+
+/* Multiplies all smooth interpolation outputs by 1/frag_w. */
+static bool
+elk_nir_lower_fs_smooth_interp_gfx4(nir_shader *shader)
+{
+   nir_def *pixel_w = NULL;
+   return nir_shader_intrinsics_pass(shader, elk_nir_lower_fs_smooth_interp_gfx4_instr,
+                                     nir_metadata_block_index | nir_metadata_dominance,
+                                     &pixel_w);
+}
+
+
 static bool
 elk_nir_lower_load_frag_coord_w_gfx4_instr(nir_builder *b, nir_intrinsic_instr *intr, void *_data)
 {
@@ -553,6 +596,7 @@ elk_nir_lower_fs_inputs(nir_shader *nir,
    NIR_PASS(_, nir, nir_lower_frag_coord_to_pixel_coord);
    if (devinfo->ver < 6) {
       /* Needs to be run before nir_lower_io. */
+      NIR_PASS(_, nir, elk_nir_lower_fs_smooth_interp_gfx4);
       NIR_PASS(_, nir, elk_nir_lower_load_frag_coord_w_gfx4);
    }