Index: lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
===================================================================
--- lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
+++ lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
@@ -106,5 +106,17 @@
   setAction({G_LOAD, 1, S64}, Legal);
   setAction({G_STORE, 1, S64}, Legal);
 
+  // FIXME: Doesn't handle extract of illegal sizes.
+  getActionDefinitionsBuilder(G_EXTRACT)
+    .unsupportedIf([=](const LegalityQuery &Query) {
+        return Query.Types[0].getSizeInBits() >= Query.Types[1].getSizeInBits();
+      })
+    .legalIf([=](const LegalityQuery &Query) {
+        const LLT &Ty0 = Query.Types[0];
+        const LLT &Ty1 = Query.Types[1];
+        return (Ty0.getSizeInBits() % 32 == 0) &&
+               (Ty1.getSizeInBits() % 32 == 0);
+      });
+
   computeTables();
 }
Index: test/CodeGen/AMDGPU/GlobalISel/legalize-extract.mir
===================================================================
--- /dev/null
+++ test/CodeGen/AMDGPU/GlobalISel/legalize-extract.mir
@@ -0,0 +1,105 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn-mesa-mesa3d -mcpu=fiji -run-pass=legalizer -global-isel %s -o - | FileCheck %s
+
+---
+name: test_extract_lo32_i64
+body: |
+  bb.0.entry:
+    liveins: $vgpr0_vgpr1
+
+    ; CHECK-LABEL: name: test_extract_lo32_i64
+    ; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $vgpr0_vgpr1
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(s32) = G_EXTRACT [[COPY]](s64), 0
+    ; CHECK: S_ENDPGM implicit [[EXTRACT]](s32)
+    %0:_(s64) = COPY $vgpr0_vgpr1
+    %1:_(s32) = G_EXTRACT %0, 0
+    S_ENDPGM implicit %1
+...
+---
+name: test_extract_hi32_i64
+body: |
+  bb.0.entry:
+    liveins: $vgpr0_vgpr1
+
+    ; CHECK-LABEL: name: test_extract_hi32_i64
+    ; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $vgpr0_vgpr1
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(s32) = G_EXTRACT [[COPY]](s64), 32
+    ; CHECK: S_ENDPGM implicit [[EXTRACT]](s32)
+    %0:_(s64) = COPY $vgpr0_vgpr1
+    %1:_(s32) = G_EXTRACT %0, 32
+     S_ENDPGM implicit %1
+...
+
+---
+name: test_extract_dword0_i128
+body: |
+  bb.0.entry:
+    liveins: $vgpr0_vgpr1
+
+    ; CHECK-LABEL: name: test_extract_dword0_i128
+    ; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $vgpr0_vgpr1
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(s32) = G_EXTRACT [[COPY]](s64), 0
+    ; CHECK: S_ENDPGM implicit [[EXTRACT]](s32)
+    %0:_(s64) = COPY $vgpr0_vgpr1
+    %1:_(s32) = G_EXTRACT %0, 0
+    S_ENDPGM implicit %1
+...
+
+---
+name: test_extract_dword1_i128
+body: |
+  bb.0.entry:
+    liveins: $vgpr0_vgpr1_vgpr2_vgpr3
+
+    ; CHECK-LABEL: name: test_extract_dword1_i128
+    ; CHECK: [[COPY:%[0-9]+]]:_(s128) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(s32) = G_EXTRACT [[COPY]](s128), 32
+    ; CHECK: S_ENDPGM implicit [[EXTRACT]](s32)
+    %0:_(s128) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+    %1:_(s32) = G_EXTRACT %0, 32
+    S_ENDPGM implicit %1
+...
+
+---
+name: test_extract_dword2_i128
+body: |
+  bb.0.entry:
+    liveins: $vgpr0_vgpr1_vgpr2_vgpr3
+
+    ; CHECK-LABEL: name: test_extract_dword2_i128
+    ; CHECK: [[COPY:%[0-9]+]]:_(s128) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(s32) = G_EXTRACT [[COPY]](s128), 64
+    ; CHECK: S_ENDPGM implicit [[EXTRACT]](s32)
+    %0:_(s128) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+    %1:_(s32) = G_EXTRACT %0, 64
+    S_ENDPGM implicit %1
+...
+
+---
+name: test_extract_dword3_i128
+body: |
+  bb.0.entry:
+    liveins: $vgpr0_vgpr1_vgpr2_vgpr3
+
+    ; CHECK-LABEL: name: test_extract_dword3_i128
+    ; CHECK: [[COPY:%[0-9]+]]:_(s128) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(s32) = G_EXTRACT [[COPY]](s128), 96
+    ; CHECK: S_ENDPGM implicit [[EXTRACT]](s32)
+    %0:_(s128) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+    %1:_(s32) = G_EXTRACT %0, 96
+     S_ENDPGM implicit %1
+...
+---
+name: test_extract_dword2_i96
+body: |
+  bb.0.entry:
+    liveins: $vgpr0_vgpr1_vgpr2
+
+    ; CHECK-LABEL: name: test_extract_dword2_i96
+    ; CHECK: [[COPY:%[0-9]+]]:_(s96) = COPY $vgpr0_vgpr1_vgpr2
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(s32) = G_EXTRACT [[COPY]](s96), 64
+    ; CHECK: S_ENDPGM implicit [[EXTRACT]](s32)
+    %0:_(s96) = COPY $vgpr0_vgpr1_vgpr2
+    %1:_(s32) = G_EXTRACT %0, 64
+    S_ENDPGM implicit %1
+...