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
@@ -289,6 +289,15 @@
     .widenScalarToNextPow2(1, /*Min=*/8)
     .clampScalar(1, s8, sMaxScalar);
 
+  // todo: vectors 
+  getActionDefinitionsBuilder(G_SELECT)
+       //    .legalFor({{s8, s8}, {s16, s16}, {s32, s32}, {s64, s64}, {p0, p0}})
+    .legalFor({s8, s16, s32, s64, p0})
+    .widenScalarToNextPow2(0, /*Min=*/8)
+    .clampScalar(0, s8, sMaxScalar)
+    .widenScalarToNextPow2(1, /*Min=*/8)
+    .clampScalar(1, s8, sMaxScalar);
+
   setLegalizerInfo32bit();
   setLegalizerInfo64bit();
   setLegalizerInfoSSE1();
diff --git a/llvm/test/CodeGen/X86/GlobalISel/legalize-leading-zeros.mir b/llvm/test/CodeGen/X86/GlobalISel/legalize-leading-zeros.mir
--- a/llvm/test/CodeGen/X86/GlobalISel/legalize-leading-zeros.mir
+++ b/llvm/test/CodeGen/X86/GlobalISel/legalize-leading-zeros.mir
@@ -1,10 +1,6 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 2
 # RUN: llc -mtriple=x86_64-linux-gnu -mattr=+lzcnt -run-pass=legalizer %s -o - | FileCheck %s --check-prefixes=CHECK,X64
 # RUN: llc -mtriple=i386-linux-gnu -mattr=+lzcnt -run-pass=legalizer -global-isel-abort=2 -pass-remarks-missed='gisel*'  %s 2>%t -o - | FileCheck %s --check-prefixes=CHECK,X86
-# RUN: FileCheck -check-prefix=ERR32  %s < %t
-
-# ERR32: remark: <unknown>:0:0: unable to legalize instruction: %13:_(s32), %14:_(s1) = G_USUBE %8:_, %10:_, %12:_ (in function: test_ctlz35)
-# ERR32: remark: <unknown>:0:0: unable to legalize instruction: %1:_(s64) = G_SELECT %6:_(s1), %9:_, %10:_ (in function: test_ctlz64)
 
 # test count leading zeros for s16, s32, and s64
 
@@ -93,8 +89,13 @@
     ; X86-NEXT: [[C1:%[0-9]+]]:_(s64) = G_CONSTANT i64 32
     ; X86-NEXT: [[ADD:%[0-9]+]]:_(s64) = G_ADD [[CTLZ]], [[C1]]
     ; X86-NEXT: [[CTLZ_ZERO_UNDEF:%[0-9]+]]:_(s64) = G_CTLZ_ZERO_UNDEF [[UV1]](s32)
-    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s64) = G_SELECT [[ICMP]](s1), [[ADD]], [[CTLZ_ZERO_UNDEF]]
-    ; X86-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY [[SELECT]](s64)
+    ; X86-NEXT: [[UV2:%[0-9]+]]:_(s32), [[UV3:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[ADD]](s64)
+    ; X86-NEXT: [[UV4:%[0-9]+]]:_(s32), [[UV5:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[CTLZ_ZERO_UNDEF]](s64)
+    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s32) = G_SELECT [[ICMP]](s1), [[UV2]], [[UV4]]
+    ; X86-NEXT: [[ZEXT:%[0-9]+]]:_(s8) = G_ZEXT [[ICMP]](s1)
+    ; X86-NEXT: [[SELECT1:%[0-9]+]]:_(s32) = G_SELECT [[ZEXT]](s8), [[UV3]], [[UV5]]
+    ; X86-NEXT: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[SELECT]](s32), [[SELECT1]](s32)
+    ; X86-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY [[MV]](s64)
     ; X86-NEXT: RET 0, implicit [[COPY]](s64)
     %0:_(s64) = IMPLICIT_DEF
     %1:_(s64) = G_CTLZ %0
diff --git a/llvm/test/CodeGen/X86/GlobalISel/legalize-select.mir b/llvm/test/CodeGen/X86/GlobalISel/legalize-select.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/GlobalISel/legalize-select.mir
@@ -0,0 +1,83 @@
+# 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-prefixes=CHECK,X86
+
+# test select
+
+...
+---
+name:            test_selectp0
+body:             |
+  bb.1:
+    ; CHECK-LABEL: name: test_selectp0
+    ; CHECK: [[DEF:%[0-9]+]]:_(s1) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[DEF1:%[0-9]+]]:_(p0) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[DEF2:%[0-9]+]]:_(p0) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[SELECT:%[0-9]+]]:_(p0) = G_SELECT [[DEF]](s1), [[DEF1]], [[DEF2]]
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(p0) = COPY [[SELECT]](p0)
+    ; CHECK-NEXT: RET 0, implicit [[COPY]](p0)
+    %0:_(s1) = IMPLICIT_DEF
+    %1:_(p0) = IMPLICIT_DEF
+    %2:_(p0) = IMPLICIT_DEF
+    %3:_(p0) = G_SELECT %0, %1, %2
+    %4:_(p0) = COPY %3(p0)
+    RET 0, implicit %4
+
+...
+---
+name:            test_selects10
+body:             |
+  bb.1:
+    ; CHECK-LABEL: name: test_selects10
+    ; CHECK: [[DEF:%[0-9]+]]:_(s1) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[DEF1:%[0-9]+]]:_(s10) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[DEF2:%[0-9]+]]:_(s10) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[ANYEXT:%[0-9]+]]:_(s16) = G_ANYEXT [[DEF1]](s10)
+    ; CHECK-NEXT: [[ANYEXT1:%[0-9]+]]:_(s16) = G_ANYEXT [[DEF2]](s10)
+    ; CHECK-NEXT: [[SELECT:%[0-9]+]]:_(s16) = G_SELECT [[DEF]](s1), [[ANYEXT]], [[ANYEXT1]]
+    ; CHECK-NEXT: [[TRUNC:%[0-9]+]]:_(s10) = G_TRUNC [[SELECT]](s16)
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s10) = COPY [[TRUNC]](s10)
+    ; CHECK-NEXT: RET 0, implicit [[COPY]](s10)
+    %0:_(s1) = IMPLICIT_DEF
+    %1:_(s10) = IMPLICIT_DEF
+    %2:_(s10) = IMPLICIT_DEF
+    %3:_(s10) = G_SELECT %0, %1, %2
+    %4:_(s10) = COPY %3(s10)
+    RET 0, implicit %4
+
+...
+---
+name:            test_select32
+body:             |
+  bb.1:
+    ; CHECK-LABEL: name: test_select32
+    ; CHECK: [[DEF:%[0-9]+]]:_(s1) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[DEF1:%[0-9]+]]:_(s32) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[DEF2:%[0-9]+]]:_(s32) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[SELECT:%[0-9]+]]:_(s32) = G_SELECT [[DEF]](s1), [[DEF1]], [[DEF2]]
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY [[SELECT]](s32)
+    ; CHECK-NEXT: RET 0, implicit [[COPY]](s32)
+    %0:_(s1) = IMPLICIT_DEF
+    %1:_(s32) = IMPLICIT_DEF
+    %2:_(s32) = IMPLICIT_DEF
+    %3:_(s32) = G_SELECT %0, %1, %2
+    %4:_(s32) = COPY %3(s32)
+    RET 0, implicit %4
+
+...
+---
+name:            test_select16
+body:             |
+  bb.1:
+    ; CHECK-LABEL: name: test_select16
+    ; CHECK: [[DEF:%[0-9]+]]:_(s1) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[DEF1:%[0-9]+]]:_(s16) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[DEF2:%[0-9]+]]:_(s16) = IMPLICIT_DEF
+    ; CHECK-NEXT: [[SELECT:%[0-9]+]]:_(s16) = G_SELECT [[DEF]](s1), [[DEF1]], [[DEF2]]
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s16) = COPY [[SELECT]](s16)
+    ; CHECK-NEXT: RET 0, implicit [[COPY]](s16)
+    %0:_(s1) = IMPLICIT_DEF
+    %1:_(s16) = IMPLICIT_DEF
+    %2:_(s16) = IMPLICIT_DEF
+    %3:_(s16) = G_SELECT %0, %1, %2
+    %4:_(s16) = COPY %3(s16)
+    RET 0, implicit %4
diff --git a/llvm/test/CodeGen/X86/GlobalISel/legalize-trailing-zeros-undef.mir b/llvm/test/CodeGen/X86/GlobalISel/legalize-trailing-zeros-undef.mir
--- a/llvm/test/CodeGen/X86/GlobalISel/legalize-trailing-zeros-undef.mir
+++ b/llvm/test/CodeGen/X86/GlobalISel/legalize-trailing-zeros-undef.mir
@@ -1,10 +1,6 @@
 # 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 --check-prefixes=CHECK,X64
 # RUN: llc -mtriple=i386-linux-gnu -run-pass=legalizer -global-isel-abort=2 -pass-remarks-missed='gisel*'  %s 2>%t -o - | FileCheck %s --check-prefixes=CHECK,X86
-# RUN: FileCheck -check-prefix=ERR32  %s < %t
-
-# ERR32: remark: <unknown>:0:0: unable to legalize instruction: %4:_(s64) = G_SELECT %8:_(s1), %11:_, %12:_ (in function: test_cttz35)
-# ERR32: remark: <unknown>:0:0: unable to legalize instruction: %1:_(s64) = G_SELECT %6:_(s1), %9:_, %10:_ (in function: test_cttz64)
 
 # test count leading zeros for s16, s32, and s64
 
@@ -35,8 +31,13 @@
     ; X86-NEXT: [[C1:%[0-9]+]]:_(s64) = G_CONSTANT i64 32
     ; X86-NEXT: [[ADD:%[0-9]+]]:_(s64) = G_ADD [[CTTZ_ZERO_UNDEF]], [[C1]]
     ; X86-NEXT: [[CTTZ_ZERO_UNDEF1:%[0-9]+]]:_(s64) = G_CTTZ_ZERO_UNDEF [[UV]](s32)
-    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s64) = G_SELECT [[ICMP]](s1), [[ADD]], [[CTTZ_ZERO_UNDEF1]]
-    ; X86-NEXT: [[TRUNC:%[0-9]+]]:_(s35) = G_TRUNC [[SELECT]](s64)
+    ; X86-NEXT: [[UV2:%[0-9]+]]:_(s32), [[UV3:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[ADD]](s64)
+    ; X86-NEXT: [[UV4:%[0-9]+]]:_(s32), [[UV5:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[CTTZ_ZERO_UNDEF1]](s64)
+    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s32) = G_SELECT [[ICMP]](s1), [[UV2]], [[UV4]]
+    ; X86-NEXT: [[ZEXT:%[0-9]+]]:_(s8) = G_ZEXT [[ICMP]](s1)
+    ; X86-NEXT: [[SELECT1:%[0-9]+]]:_(s32) = G_SELECT [[ZEXT]](s8), [[UV3]], [[UV5]]
+    ; X86-NEXT: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[SELECT]](s32), [[SELECT1]](s32)
+    ; X86-NEXT: [[TRUNC:%[0-9]+]]:_(s35) = G_TRUNC [[MV]](s64)
     ; X86-NEXT: [[COPY:%[0-9]+]]:_(s35) = COPY [[TRUNC]](s35)
     ; X86-NEXT: RET 0, implicit [[COPY]](s35)
     %0:_(s35) = IMPLICIT_DEF
@@ -90,8 +91,13 @@
     ; X86-NEXT: [[C1:%[0-9]+]]:_(s64) = G_CONSTANT i64 32
     ; X86-NEXT: [[ADD:%[0-9]+]]:_(s64) = G_ADD [[CTTZ_ZERO_UNDEF]], [[C1]]
     ; X86-NEXT: [[CTTZ_ZERO_UNDEF1:%[0-9]+]]:_(s64) = G_CTTZ_ZERO_UNDEF [[UV]](s32)
-    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s64) = G_SELECT [[ICMP]](s1), [[ADD]], [[CTTZ_ZERO_UNDEF1]]
-    ; X86-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY [[SELECT]](s64)
+    ; X86-NEXT: [[UV2:%[0-9]+]]:_(s32), [[UV3:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[ADD]](s64)
+    ; X86-NEXT: [[UV4:%[0-9]+]]:_(s32), [[UV5:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[CTTZ_ZERO_UNDEF1]](s64)
+    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s32) = G_SELECT [[ICMP]](s1), [[UV2]], [[UV4]]
+    ; X86-NEXT: [[ZEXT:%[0-9]+]]:_(s8) = G_ZEXT [[ICMP]](s1)
+    ; X86-NEXT: [[SELECT1:%[0-9]+]]:_(s32) = G_SELECT [[ZEXT]](s8), [[UV3]], [[UV5]]
+    ; X86-NEXT: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[SELECT]](s32), [[SELECT1]](s32)
+    ; X86-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY [[MV]](s64)
     ; X86-NEXT: RET 0, implicit [[COPY]](s64)
     %0:_(s64) = IMPLICIT_DEF
     %1:_(s64) = G_CTTZ_ZERO_UNDEF %0
diff --git a/llvm/test/CodeGen/X86/GlobalISel/legalize-trailing-zeros.mir b/llvm/test/CodeGen/X86/GlobalISel/legalize-trailing-zeros.mir
--- a/llvm/test/CodeGen/X86/GlobalISel/legalize-trailing-zeros.mir
+++ b/llvm/test/CodeGen/X86/GlobalISel/legalize-trailing-zeros.mir
@@ -1,10 +1,6 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 2
 # RUN: llc -mtriple=x86_64-linux-gnu -mattr=+bmi -run-pass=legalizer %s -o - | FileCheck %s --check-prefixes=CHECK,X64
 # RUN: llc -mtriple=i386-linux-gnu -mattr=+bmi -run-pass=legalizer -global-isel-abort=2 -pass-remarks-missed='gisel*'  %s 2>%t -o - | FileCheck %s --check-prefixes=CHECK,X86
-# RUN: FileCheck -check-prefix=ERR32  %s < %t
-
-# ERR32: remark: <unknown>:0:0: unable to legalize instruction: %6:_(s64) = G_SELECT %10:_(s1), %13:_, %14:_ (in function: test_cttz35)
-# ERR32: remark: <unknown>:0:0: unable to legalize instruction: %1:_(s64) = G_SELECT %6:_(s1), %9:_, %10:_ (in function: test_cttz64)
 
 # test count leading zeros for s16, s32, and s64
 
@@ -39,8 +35,13 @@
     ; X86-NEXT: [[C2:%[0-9]+]]:_(s64) = G_CONSTANT i64 32
     ; X86-NEXT: [[ADD:%[0-9]+]]:_(s64) = G_ADD [[CTTZ_ZERO_UNDEF]], [[C2]]
     ; X86-NEXT: [[CTTZ_ZERO_UNDEF1:%[0-9]+]]:_(s64) = G_CTTZ_ZERO_UNDEF [[UV]](s32)
-    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s64) = G_SELECT [[ICMP]](s1), [[ADD]], [[CTTZ_ZERO_UNDEF1]]
-    ; X86-NEXT: [[TRUNC:%[0-9]+]]:_(s35) = G_TRUNC [[SELECT]](s64)
+    ; X86-NEXT: [[UV2:%[0-9]+]]:_(s32), [[UV3:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[ADD]](s64)
+    ; X86-NEXT: [[UV4:%[0-9]+]]:_(s32), [[UV5:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[CTTZ_ZERO_UNDEF1]](s64)
+    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s32) = G_SELECT [[ICMP]](s1), [[UV2]], [[UV4]]
+    ; X86-NEXT: [[ZEXT:%[0-9]+]]:_(s8) = G_ZEXT [[ICMP]](s1)
+    ; X86-NEXT: [[SELECT1:%[0-9]+]]:_(s32) = G_SELECT [[ZEXT]](s8), [[UV3]], [[UV5]]
+    ; X86-NEXT: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[SELECT]](s32), [[SELECT1]](s32)
+    ; X86-NEXT: [[TRUNC:%[0-9]+]]:_(s35) = G_TRUNC [[MV]](s64)
     ; X86-NEXT: [[COPY:%[0-9]+]]:_(s35) = COPY [[TRUNC]](s35)
     ; X86-NEXT: RET 0, implicit [[COPY]](s35)
     %0:_(s35) = IMPLICIT_DEF
@@ -96,8 +97,13 @@
     ; X86-NEXT: [[C1:%[0-9]+]]:_(s64) = G_CONSTANT i64 32
     ; X86-NEXT: [[ADD:%[0-9]+]]:_(s64) = G_ADD [[CTTZ]], [[C1]]
     ; X86-NEXT: [[CTTZ_ZERO_UNDEF:%[0-9]+]]:_(s64) = G_CTTZ_ZERO_UNDEF [[UV]](s32)
-    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s64) = G_SELECT [[ICMP]](s1), [[ADD]], [[CTTZ_ZERO_UNDEF]]
-    ; X86-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY [[SELECT]](s64)
+    ; X86-NEXT: [[UV2:%[0-9]+]]:_(s32), [[UV3:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[ADD]](s64)
+    ; X86-NEXT: [[UV4:%[0-9]+]]:_(s32), [[UV5:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[CTTZ_ZERO_UNDEF]](s64)
+    ; X86-NEXT: [[SELECT:%[0-9]+]]:_(s32) = G_SELECT [[ICMP]](s1), [[UV2]], [[UV4]]
+    ; X86-NEXT: [[ZEXT:%[0-9]+]]:_(s8) = G_ZEXT [[ICMP]](s1)
+    ; X86-NEXT: [[SELECT1:%[0-9]+]]:_(s32) = G_SELECT [[ZEXT]](s8), [[UV3]], [[UV5]]
+    ; X86-NEXT: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[SELECT]](s32), [[SELECT1]](s32)
+    ; X86-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY [[MV]](s64)
     ; X86-NEXT: RET 0, implicit [[COPY]](s64)
     %0:_(s64) = IMPLICIT_DEF
     %1:_(s64) = G_CTTZ %0