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
@@ -77,6 +77,7 @@
   const LLT s16 = LLT::scalar(16);
   const LLT s32 = LLT::scalar(32);
   const LLT s64 = LLT::scalar(64);
+  const LLT s128 = LLT::scalar(128);
   const LLT sMaxScalar = Subtarget.is64Bit() ? s64 : s32;
 
   const LLT v16s8 = LLT::fixed_vector(16, 8);
@@ -258,6 +259,18 @@
 
   getActionDefinitionsBuilder(G_INTTOPTR).legalFor({{p0, sMaxScalar}});
 
+  // sext, zext, and anyext
+  getActionDefinitionsBuilder({G_SEXT, G_ZEXT, G_ANYEXT})
+      .legalIf([=](const LegalityQuery &Query) {
+        return typeInSet(0, {s8, s16, s32})(Query) ||
+          (Query.Opcode == G_ANYEXT && Query.Types[0] == s128) ||
+          (Is64Bit && Query.Types[0] == s64);
+      })
+    .widenScalarToNextPow2(0, /*Min=*/8)
+    .clampScalar(0, s8, sMaxScalar)
+    .widenScalarToNextPow2(1, /*Min=*/8)
+    .clampScalar(1, s8, sMaxScalar);
+
   setLegalizerInfo32bit();
   setLegalizerInfo64bit();
   setLegalizerInfoSSE1();
@@ -302,7 +315,6 @@
   const LLT s16 = LLT::scalar(16);
   const LLT s32 = LLT::scalar(32);
   const LLT s64 = LLT::scalar(64);
-  const LLT s128 = LLT::scalar(128);
 
   auto &LegacyInfo = getLegacyLegalizerInfo();
 
@@ -340,13 +352,6 @@
     LegacyInfo.setAction({TargetOpcode::G_CONSTANT, Ty},
                          LegacyLegalizeActions::Legal);
 
-  // Extensions
-  for (auto Ty : {s8, s16, s32}) {
-    LegacyInfo.setAction({G_ZEXT, Ty}, LegacyLegalizeActions::Legal);
-    LegacyInfo.setAction({G_SEXT, Ty}, LegacyLegalizeActions::Legal);
-    LegacyInfo.setAction({G_ANYEXT, Ty}, LegacyLegalizeActions::Legal);
-  }
-  LegacyInfo.setAction({G_ANYEXT, s128}, LegacyLegalizeActions::Legal);
   getActionDefinitionsBuilder(G_SEXT_INREG).lower();
 
   // Merge/Unmerge
@@ -390,11 +395,6 @@
   LegacyInfo.setAction({TargetOpcode::G_CONSTANT, s64},
                        LegacyLegalizeActions::Legal);
 
-  // Extensions
-  for (unsigned extOp : {G_ZEXT, G_SEXT, G_ANYEXT}) {
-    LegacyInfo.setAction({extOp, s64}, LegacyLegalizeActions::Legal);
-  }
-
   getActionDefinitionsBuilder(G_SITOFP)
     .legalForCartesianProduct({s32, s64})
       .clampScalar(1, s32, s64)
diff --git a/llvm/test/CodeGen/X86/GlobalISel/legalize-szanyext.mir b/llvm/test/CodeGen/X86/GlobalISel/legalize-szanyext.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/GlobalISel/legalize-szanyext.mir
@@ -0,0 +1,110 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 2
+# RUN: llc -mtriple=i386-linux-gnu -run-pass=legalizer %s -o - | FileCheck %s --check-prefix=X86-32
+# RUN: llc -mtriple=x86_64-linux-gnu -run-pass=legalizer %s -o - | FileCheck %s --check-prefix=X86-64
+
+# test exts
+
+...
+---
+name:            test_zext12
+body:             |
+  bb.1:
+    ; X86-32-LABEL: name: test_zext12
+    ; X86-32: [[DEF:%[0-9]+]]:_(s12) = IMPLICIT_DEF
+    ; X86-32-NEXT: [[ZEXT:%[0-9]+]]:_(s32) = G_ZEXT [[DEF]](s12)
+    ; X86-32-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY [[ZEXT]](s32)
+    ; X86-32-NEXT: RET 0, implicit [[COPY]](s32)
+    ; X86-64-LABEL: name: test_zext12
+    ; X86-64: [[DEF:%[0-9]+]]:_(s12) = IMPLICIT_DEF
+    ; X86-64-NEXT: [[ZEXT:%[0-9]+]]:_(s32) = G_ZEXT [[DEF]](s12)
+    ; X86-64-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY [[ZEXT]](s32)
+    ; X86-64-NEXT: RET 0, implicit [[COPY]](s32)
+    %0:_(s12) = IMPLICIT_DEF
+    %1:_(s32) = G_ZEXT %0
+    %2:_(s32) = COPY %1(s32)
+    RET 0, implicit %2
+
+...
+---
+name:            test_anyext16
+body:             |
+  bb.1:
+    ; X86-32-LABEL: name: test_anyext16
+    ; X86-32: [[DEF:%[0-9]+]]:_(s16) = IMPLICIT_DEF
+    ; X86-32-NEXT: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[DEF]](s16)
+    ; X86-32-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY [[ANYEXT]](s32)
+    ; X86-32-NEXT: RET 0, implicit [[COPY]](s32)
+    ; X86-64-LABEL: name: test_anyext16
+    ; X86-64: [[DEF:%[0-9]+]]:_(s16) = IMPLICIT_DEF
+    ; X86-64-NEXT: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[DEF]](s16)
+    ; X86-64-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY [[ANYEXT]](s32)
+    ; X86-64-NEXT: RET 0, implicit [[COPY]](s32)
+    %0:_(s16) = IMPLICIT_DEF
+    %1:_(s32) = G_ANYEXT %0
+    %2:_(s32) = COPY %1(s32)
+    RET 0, implicit %2
+
+...
+---
+name:            test_sext16b
+body:             |
+  bb.1:
+    ; X86-32-LABEL: name: test_sext16b
+    ; X86-32: [[DEF:%[0-9]+]]:_(s16) = IMPLICIT_DEF
+    ; X86-32-NEXT: [[C:%[0-9]+]]:_(s16) = G_CONSTANT i16 0
+    ; X86-32-NEXT: [[MV:%[0-9]+]]:_(s32) = G_MERGE_VALUES [[DEF]](s16), [[C]](s16)
+    ; X86-32-NEXT: [[C1:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
+    ; X86-32-NEXT: [[MV1:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[MV]](s32), [[C1]](s32)
+    ; X86-32-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY [[MV1]](s64)
+    ; X86-32-NEXT: RET 0, implicit [[COPY]](s64)
+    ; X86-64-LABEL: name: test_sext16b
+    ; X86-64: [[DEF:%[0-9]+]]:_(s16) = IMPLICIT_DEF
+    ; X86-64-NEXT: [[ZEXT:%[0-9]+]]:_(s64) = G_ZEXT [[DEF]](s16)
+    ; X86-64-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY [[ZEXT]](s64)
+    ; X86-64-NEXT: RET 0, implicit [[COPY]](s64)
+    %0:_(s16) = IMPLICIT_DEF
+    %1:_(s64) = G_ZEXT %0
+    %2:_(s64) = COPY %1(s64)
+    RET 0, implicit %2
+
+...
+---
+name:            test_zext18
+body:             |
+  bb.1:
+    ; X86-32-LABEL: name: test_zext18
+    ; X86-32: [[DEF:%[0-9]+]]:_(s8) = IMPLICIT_DEF
+    ; X86-32-NEXT: [[ZEXT:%[0-9]+]]:_(s16) = G_ZEXT [[DEF]](s8)
+    ; X86-32-NEXT: [[COPY:%[0-9]+]]:_(s16) = COPY [[ZEXT]](s16)
+    ; X86-32-NEXT: RET 0, implicit [[COPY]](s16)
+    ; X86-64-LABEL: name: test_zext18
+    ; X86-64: [[DEF:%[0-9]+]]:_(s8) = IMPLICIT_DEF
+    ; X86-64-NEXT: [[ZEXT:%[0-9]+]]:_(s16) = G_ZEXT [[DEF]](s8)
+    ; X86-64-NEXT: [[COPY:%[0-9]+]]:_(s16) = COPY [[ZEXT]](s16)
+    ; X86-64-NEXT: RET 0, implicit [[COPY]](s16)
+    %0:_(s8) = IMPLICIT_DEF
+    %1:_(s16) = G_ZEXT %0
+    %2:_(s16) = COPY %1(s16)
+    RET 0, implicit %2
+
+...
+---
+name:            test_sext16
+body:             |
+  bb.1:
+    ; X86-32-LABEL: name: test_sext16
+    ; X86-32: [[DEF:%[0-9]+]]:_(s8) = IMPLICIT_DEF
+    ; X86-32-NEXT: [[SEXT:%[0-9]+]]:_(s16) = G_SEXT [[DEF]](s8)
+    ; X86-32-NEXT: [[COPY:%[0-9]+]]:_(s16) = COPY [[SEXT]](s16)
+    ; X86-32-NEXT: RET 0, implicit [[COPY]](s16)
+    ; X86-64-LABEL: name: test_sext16
+    ; X86-64: [[DEF:%[0-9]+]]:_(s8) = IMPLICIT_DEF
+    ; X86-64-NEXT: [[SEXT:%[0-9]+]]:_(s16) = G_SEXT [[DEF]](s8)
+    ; X86-64-NEXT: [[COPY:%[0-9]+]]:_(s16) = COPY [[SEXT]](s16)
+    ; X86-64-NEXT: RET 0, implicit [[COPY]](s16)
+    %0:_(s8) = IMPLICIT_DEF
+    %1:_(s16) = G_SEXT %0
+    %2:_(s16) = COPY %1(s16)
+    RET 0, implicit %2
+
+...