diff --git a/llvm/lib/Target/X86/X86LegalizerInfo.cpp b/llvm/lib/Target/X86/X86LegalizerInfo.cpp
--- a/llvm/lib/Target/X86/X86LegalizerInfo.cpp
+++ b/llvm/lib/Target/X86/X86LegalizerInfo.cpp
@@ -286,6 +286,12 @@
                        LegacyLegalizeActions::Legal);
   LegacyInfo.setAction({G_MERGE_VALUES, 1, s128}, LegacyLegalizeActions::Legal);
   LegacyInfo.setAction({G_UNMERGE_VALUES, s128}, LegacyLegalizeActions::Legal);
+
+  getActionDefinitionsBuilder({G_BSWAP})
+    .legalFor({s32, s64})
+    .widenScalarToNextPow2(1, /*Min=*/32)
+    .clampScalar(0, s32, s64);
+
 }
 
 void X86LegalizerInfo::setLegalizerInfoSSE1() {
diff --git a/llvm/test/CodeGen/X86/GlobalISel/legalize-bswap.mir b/llvm/test/CodeGen/X86/GlobalISel/legalize-bswap.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/GlobalISel/legalize-bswap.mir
@@ -0,0 +1,113 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 2
+# RUN: llc -mtriple=x86_64-linux-gnu -run-pass=legalizer %s -o - | FileCheck %s
+
+# test BSWAP s32 and s64
+
+---
+name:            test_bswap_s96
+alignment:       16
+legalized:       false
+regBankSelected: false
+registers:
+  - { id: 0, class: _, preferred-register: '' }
+  - { id: 1, class: _, preferred-register: '' }
+liveins:
+fixedStack:
+stack:
+constants:
+body:             |
+  bb.1:
+    ; CHECK-LABEL: name: test_bswap_s96
+    ; CHECK: [[DEF:%[0-9]+]]:_(s96) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[DEF]](s96)
+    ; CHECK-NEXT: [[BSWAP:%[0-9]+]]:_(s32) = G_BSWAP [[ANYEXT]]
+    ; CHECK-NEXT: [[C:%[0-9]+]]:_(s8) = G_CONSTANT i8 -64
+    ; CHECK-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BSWAP]], [[C]](s8)
+    ; CHECK-NEXT: [[TRUNC:%[0-9]+]]:_(s96) = G_TRUNC [[LSHR]](s32)
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s96) = COPY [[TRUNC]](s96)
+    ; CHECK-NEXT: RET 0, implicit [[COPY]](s96)
+    %0:_(s96) = IMPLICIT_DEF
+    %1:_(s96) = G_BSWAP %0
+    %2:_(s96) = COPY %1(s96)
+    RET 0, implicit %2
+
+...
+---
+name:            test_bswaps64
+alignment:       16
+legalized:       false
+regBankSelected: false
+registers:
+  - { id: 0, class: _, preferred-register: '' }
+  - { id: 1, class: _, preferred-register: '' }
+liveins:
+fixedStack:
+stack:
+constants:
+body:             |
+  bb.1:
+    ; CHECK-LABEL: name: test_bswaps64
+    ; CHECK: [[DEF:%[0-9]+]]:_(s64) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[BSWAP:%[0-9]+]]:_(s64) = G_BSWAP [[DEF]]
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY [[BSWAP]](s64)
+    ; CHECK-NEXT: RET 0, implicit [[COPY]](s64)
+    %0:_(s64) = IMPLICIT_DEF
+    %1:_(s64) = G_BSWAP %0
+    %2:_(s64) = COPY %1(s64)
+    RET 0, implicit %2
+
+...
+---
+name:            test_bswap_s32
+alignment:       16
+legalized:       false
+regBankSelected: false
+registers:
+  - { id: 0, class: _, preferred-register: '' }
+  - { id: 1, class: _, preferred-register: '' }
+liveins:
+fixedStack:
+stack:
+constants:
+body:             |
+  bb.1:
+    ; CHECK-LABEL: name: test_bswap_s32
+    ; CHECK: [[DEF:%[0-9]+]]:_(s32) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[BSWAP:%[0-9]+]]:_(s32) = G_BSWAP [[DEF]]
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY [[BSWAP]](s32)
+    ; CHECK-NEXT: RET 0, implicit [[COPY]](s32)
+    %0:_(s32) = IMPLICIT_DEF
+    %1:_(s32) = G_BSWAP %0
+    %2:_(s32) = COPY %1(s32)
+    RET 0, implicit %2
+
+...
+---
+name:            test_bswap_s16
+alignment:       16
+legalized:       false
+regBankSelected: false
+registers:
+  - { id: 0, class: _, preferred-register: '' }
+  - { id: 1, class: _, preferred-register: '' }
+liveins:
+fixedStack:
+stack:
+constants:
+body:             |
+  bb.1:
+    ; CHECK-LABEL: name: test_bswap_s16
+    ; CHECK: [[DEF:%[0-9]+]]:_(s16) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[DEF]](s16)
+    ; CHECK-NEXT: [[BSWAP:%[0-9]+]]:_(s32) = G_BSWAP [[ANYEXT]]
+    ; CHECK-NEXT: [[C:%[0-9]+]]:_(s8) = G_CONSTANT i8 16
+    ; CHECK-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BSWAP]], [[C]](s8)
+    ; CHECK-NEXT: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR]](s32)
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s16) = COPY [[TRUNC]](s16)
+    ; CHECK-NEXT: RET 0, implicit [[COPY]](s16)
+    %0:_(s16) = IMPLICIT_DEF
+    %1:_(s16) = G_BSWAP %0
+    %2:_(s16) = COPY %1(s16)
+    RET 0, implicit %2
+
+...