Index: llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
===================================================================
--- llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
+++ llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
@@ -95,10 +95,17 @@
             return std::make_pair(0, EltTy);
           });
 
-  getActionDefinitionsBuilder(G_PHI).legalFor({p0, s16, s32, s64})
+  getActionDefinitionsBuilder(G_PHI)
+      .legalFor({p0, s16, s32, s64})
       .legalFor(PackedVectorAllTypeList)
       .widenScalarToNextPow2(0)
-      .clampScalar(0, s16, s64);
+      .clampScalar(0, s16, s64)
+      // Maximum: sN * k = 128
+      .clampMaxNumElements(0, s8, 16)
+      .clampMaxNumElements(0, s16, 8)
+      .clampMaxNumElements(0, s32, 4)
+      .clampMaxNumElements(0, s64, 2)
+      .clampMaxNumElements(0, p0, 2);
 
   getActionDefinitionsBuilder(G_BSWAP)
       .legalFor({s32, s64, v4s32, v2s32, v2s64})
Index: llvm/test/CodeGen/AArch64/GlobalISel/legalize-phi.mir
===================================================================
--- llvm/test/CodeGen/AArch64/GlobalISel/legalize-phi.mir
+++ llvm/test/CodeGen/AArch64/GlobalISel/legalize-phi.mir
@@ -1,5 +1,5 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
-# RUN: llc -O0 -mtriple=aarch64-unknown-unknown -verify-machineinstrs -global-isel-abort=1 -run-pass=legalizer %s -o - | FileCheck %s
+# RUN: llc -O0 -mtriple=aarch64-unknown-unknown -verify-machineinstrs -global-isel-abort=0 -run-pass=legalizer %s -o - | FileCheck %s
 ---
 name:            legalize_phi
 alignment:       4
@@ -665,3 +665,227 @@
     %trunc:_(s64) = G_TRUNC %phi
     $x0 = COPY %trunc
     RET_ReallyLR implicit $x0
+...
+---
+name:            v4s64
+alignment:       4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: v4s64
+  ; CHECK: bb.0:
+  ; CHECK:   successors: %bb.1(0x50000000), %bb.2(0x30000000)
+  ; CHECK:   liveins: $x0, $x1
+  ; CHECK:   %ptr1:_(p0) = COPY $x1
+  ; CHECK:   %ptr2:_(p0) = COPY $x0
+  ; CHECK:   %cond:_(s1) = G_IMPLICIT_DEF
+  ; CHECK:   [[LOAD:%[0-9]+]]:_(<2 x s64>) = G_LOAD %ptr1(p0) :: (load (<2 x s64>), align 32)
+  ; CHECK:   [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 16
+  ; CHECK:   [[PTR_ADD:%[0-9]+]]:_(p0) = G_PTR_ADD %ptr1, [[C]](s64)
+  ; CHECK:   [[LOAD1:%[0-9]+]]:_(<2 x s64>) = G_LOAD [[PTR_ADD]](p0) :: (load (<2 x s64>) from unknown-address + 16)
+  ; CHECK:   G_BRCOND %cond(s1), %bb.2
+  ; CHECK:   G_BR %bb.1
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   [[LOAD2:%[0-9]+]]:_(<2 x s64>) = G_LOAD %ptr2(p0) :: (load (<2 x s64>), align 32)
+  ; CHECK:   [[C1:%[0-9]+]]:_(s64) = G_CONSTANT i64 16
+  ; CHECK:   [[PTR_ADD1:%[0-9]+]]:_(p0) = G_PTR_ADD %ptr2, [[C1]](s64)
+  ; CHECK:   [[LOAD3:%[0-9]+]]:_(<2 x s64>) = G_LOAD [[PTR_ADD1]](p0) :: (load (<2 x s64>) from unknown-address + 16)
+  ; CHECK: bb.2:
+  ; CHECK:   [[PHI:%[0-9]+]]:_(<2 x s64>) = G_PHI [[LOAD2]](<2 x s64>), %bb.1, [[LOAD]](<2 x s64>), %bb.0
+  ; CHECK:   [[PHI1:%[0-9]+]]:_(<2 x s64>) = G_PHI [[LOAD3]](<2 x s64>), %bb.1, [[LOAD1]](<2 x s64>), %bb.0
+  ; CHECK:   $q0 = COPY [[PHI]](<2 x s64>)
+  ; CHECK:   $q1 = COPY [[PHI1]](<2 x s64>)
+  ; CHECK:   RET_ReallyLR implicit $q0, implicit $q1
+  bb.0:
+    successors: %bb.1(0x50000000), %bb.2(0x30000000)
+    liveins: $x0, $x1
+
+    %ptr1:_(p0) = COPY $x1
+    %ptr2:_(p0) = COPY $x0
+    %cond:_(s1) = G_IMPLICIT_DEF
+    %val_1:_(<4 x s64>) = G_LOAD %ptr1(p0) :: (load (<4 x s64>))
+    G_BRCOND %cond(s1), %bb.2
+    G_BR %bb.1
+  bb.1:
+    %val_2:_(<4 x s64>) = G_LOAD %ptr2(p0) :: (load (<4 x s64>))
+  bb.2:
+    %phi:_(<4 x s64>) = G_PHI %val_2(<4 x s64>), %bb.1, %val_1(<4 x s64>), %bb.0
+    %unmerge_1:_(<2 x s64>), %unmerge_2:_(<2 x s64>) = G_UNMERGE_VALUES %phi(<4 x s64>)
+    $q0 = COPY %unmerge_1(<2 x s64>)
+    $q1 = COPY %unmerge_2(<2 x s64>)
+    RET_ReallyLR implicit $q0, implicit $q1
+...
+---
+name:            v8s32
+alignment:       4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: v8s32
+  ; CHECK: bb.0:
+  ; CHECK:   successors: %bb.1(0x50000000), %bb.2(0x30000000)
+  ; CHECK:   liveins: $x0, $x1
+  ; CHECK:   %cond:_(s1) = G_IMPLICIT_DEF
+  ; CHECK:   [[DEF:%[0-9]+]]:_(s32) = G_IMPLICIT_DEF
+  ; CHECK:   [[BUILD_VECTOR:%[0-9]+]]:_(<4 x s32>) = G_BUILD_VECTOR [[DEF]](s32), [[DEF]](s32), [[DEF]](s32), [[DEF]](s32)
+  ; CHECK:   [[BUILD_VECTOR1:%[0-9]+]]:_(<4 x s32>) = G_BUILD_VECTOR [[DEF]](s32), [[DEF]](s32), [[DEF]](s32), [[DEF]](s32)
+  ; CHECK:   G_BRCOND %cond(s1), %bb.2
+  ; CHECK:   G_BR %bb.1
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   [[DEF1:%[0-9]+]]:_(s32) = G_IMPLICIT_DEF
+  ; CHECK:   [[BUILD_VECTOR2:%[0-9]+]]:_(<4 x s32>) = G_BUILD_VECTOR [[DEF1]](s32), [[DEF1]](s32), [[DEF1]](s32), [[DEF1]](s32)
+  ; CHECK:   [[BUILD_VECTOR3:%[0-9]+]]:_(<4 x s32>) = G_BUILD_VECTOR [[DEF1]](s32), [[DEF1]](s32), [[DEF1]](s32), [[DEF1]](s32)
+  ; CHECK: bb.2:
+  ; CHECK:   [[PHI:%[0-9]+]]:_(<4 x s32>) = G_PHI [[BUILD_VECTOR2]](<4 x s32>), %bb.1, [[BUILD_VECTOR]](<4 x s32>), %bb.0
+  ; CHECK:   [[PHI1:%[0-9]+]]:_(<4 x s32>) = G_PHI [[BUILD_VECTOR3]](<4 x s32>), %bb.1, [[BUILD_VECTOR1]](<4 x s32>), %bb.0
+  ; CHECK:   %one:_(s32) = G_CONSTANT i32 1
+  ; CHECK:   [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 1
+  ; CHECK:   %extract:_(s32) = G_EXTRACT_VECTOR_ELT [[PHI]](<4 x s32>), [[C]](s64)
+  ; CHECK:   $w0 = COPY %extract(s32)
+  ; CHECK:   RET_ReallyLR implicit $w0
+  bb.0:
+    successors: %bb.1(0x50000000), %bb.2(0x30000000)
+    liveins: $x0, $x1
+    %cond:_(s1) = G_IMPLICIT_DEF
+    %val_1:_(<8 x s32>) = G_IMPLICIT_DEF
+    G_BRCOND %cond(s1), %bb.2
+    G_BR %bb.1
+  bb.1:
+    %val_2:_(<8 x s32>) = G_IMPLICIT_DEF
+  bb.2:
+    %phi:_(<8 x s32>) = G_PHI %val_2(<8 x s32>), %bb.1, %val_1(<8 x s32>), %bb.0
+    %one:_(s32) = G_CONSTANT i32 1
+    %extract:_(s32) = G_EXTRACT_VECTOR_ELT %phi(<8 x s32>), %one(s32)
+    $w0 = COPY %extract
+    RET_ReallyLR implicit $w0
+...
+---
+name:            v16s16
+alignment:       4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: v16s16
+  ; CHECK: bb.0:
+  ; CHECK:   successors: %bb.1(0x50000000), %bb.2(0x30000000)
+  ; CHECK:   liveins: $x0, $x1
+  ; CHECK:   %cond:_(s1) = G_IMPLICIT_DEF
+  ; CHECK:   [[DEF:%[0-9]+]]:_(s16) = G_IMPLICIT_DEF
+  ; CHECK:   [[BUILD_VECTOR:%[0-9]+]]:_(<8 x s16>) = G_BUILD_VECTOR [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16)
+  ; CHECK:   [[BUILD_VECTOR1:%[0-9]+]]:_(<8 x s16>) = G_BUILD_VECTOR [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16), [[DEF]](s16)
+  ; CHECK:   G_BRCOND %cond(s1), %bb.2
+  ; CHECK:   G_BR %bb.1
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   [[DEF1:%[0-9]+]]:_(s16) = G_IMPLICIT_DEF
+  ; CHECK:   [[BUILD_VECTOR2:%[0-9]+]]:_(<8 x s16>) = G_BUILD_VECTOR [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16)
+  ; CHECK:   [[BUILD_VECTOR3:%[0-9]+]]:_(<8 x s16>) = G_BUILD_VECTOR [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16), [[DEF1]](s16)
+  ; CHECK: bb.2:
+  ; CHECK:   [[PHI:%[0-9]+]]:_(<8 x s16>) = G_PHI [[BUILD_VECTOR2]](<8 x s16>), %bb.1, [[BUILD_VECTOR]](<8 x s16>), %bb.0
+  ; CHECK:   [[PHI1:%[0-9]+]]:_(<8 x s16>) = G_PHI [[BUILD_VECTOR3]](<8 x s16>), %bb.1, [[BUILD_VECTOR1]](<8 x s16>), %bb.0
+  ; CHECK:   %one:_(s16) = G_CONSTANT i16 1
+  ; CHECK:   [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 1
+  ; CHECK:   %extract:_(s16) = G_EXTRACT_VECTOR_ELT [[PHI]](<8 x s16>), [[C]](s64)
+  ; CHECK:   $h0 = COPY %extract(s16)
+  ; CHECK:   RET_ReallyLR implicit $h0
+  bb.0:
+    successors: %bb.1(0x50000000), %bb.2(0x30000000)
+    liveins: $x0, $x1
+    %cond:_(s1) = G_IMPLICIT_DEF
+    %val_1:_(<16 x s16>) = G_IMPLICIT_DEF
+    G_BRCOND %cond(s1), %bb.2
+    G_BR %bb.1
+  bb.1:
+    %val_2:_(<16 x s16>) = G_IMPLICIT_DEF
+  bb.2:
+    %phi:_(<16 x s16>) = G_PHI %val_2(<16 x s16>), %bb.1, %val_1(<16 x s16>), %bb.0
+    %one:_(s16) = G_CONSTANT i16 1
+    %extract:_(s16) = G_EXTRACT_VECTOR_ELT %phi(<16 x s16>), %one(s16)
+    $h0 = COPY %extract
+    RET_ReallyLR implicit $h0
+...
+---
+name:            v32s8
+alignment:       4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: v32s8
+  ; CHECK: bb.0:
+  ; CHECK:   successors: %bb.1(0x50000000), %bb.2(0x30000000)
+  ; CHECK:   liveins: $x0, $x1
+  ; CHECK:   %cond:_(s1) = G_IMPLICIT_DEF
+  ; CHECK:   %val_1:_(<32 x s8>) = G_IMPLICIT_DEF
+  ; CHECK:   G_BRCOND %cond(s1), %bb.2
+  ; CHECK:   G_BR %bb.1
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   %val_2:_(<32 x s8>) = G_IMPLICIT_DEF
+  ; CHECK: bb.2:
+  ; CHECK:   %phi:_(<32 x s8>) = G_PHI %val_2(<32 x s8>), %bb.1, %val_1(<32 x s8>), %bb.0
+  ; CHECK:   %one:_(s8) = G_CONSTANT i8 1
+  ; CHECK:   [[SEXT:%[0-9]+]]:_(s64) = G_SEXT %one(s8)
+  ; CHECK:   %extract:_(s8) = G_EXTRACT_VECTOR_ELT %phi(<32 x s8>), [[SEXT]](s64)
+  ; CHECK:   $b0 = COPY %extract(s8)
+  ; CHECK:   RET_ReallyLR implicit $b0
+  bb.0:
+    successors: %bb.1(0x50000000), %bb.2(0x30000000)
+    liveins: $x0, $x1
+    %cond:_(s1) = G_IMPLICIT_DEF
+    %val_1:_(<32 x s8>) = G_IMPLICIT_DEF
+    G_BRCOND %cond(s1), %bb.2
+    G_BR %bb.1
+  bb.1:
+    %val_2:_(<32 x s8>) = G_IMPLICIT_DEF
+  bb.2:
+    %phi:_(<32 x s8>) = G_PHI %val_2(<32 x s8>), %bb.1, %val_1(<32 x s8>), %bb.0
+    %one:_(s8) = G_CONSTANT i8 1
+    %extract:_(s8) = G_EXTRACT_VECTOR_ELT %phi(<32 x s8>), %one(s8)
+    $b0 = COPY %extract
+    RET_ReallyLR implicit $b0
+...
+---
+name:            v4p0
+alignment:       4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: v4p0
+  ; CHECK: bb.0:
+  ; CHECK:   successors: %bb.1(0x50000000), %bb.2(0x30000000)
+  ; CHECK:   liveins: $x0, $x1
+  ; CHECK:   %ptr1:_(p0) = COPY $x1
+  ; CHECK:   %ptr2:_(p0) = COPY $x0
+  ; CHECK:   %cond:_(s1) = G_IMPLICIT_DEF
+  ; CHECK:   %val_1:_(<4 x p0>) = G_LOAD %ptr1(p0) :: (load (<4 x p0>))
+  ; CHECK:   [[UV:%[0-9]+]]:_(<2 x p0>), [[UV1:%[0-9]+]]:_(<2 x p0>) = G_UNMERGE_VALUES %val_1(<4 x p0>)
+  ; CHECK:   G_BRCOND %cond(s1), %bb.2
+  ; CHECK:   G_BR %bb.1
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   [[LOAD:%[0-9]+]]:_(<4 x s64>) = G_LOAD %ptr2(p0) :: (load (<4 x s64>))
+  ; CHECK:   %val_2:_(<4 x p0>) = G_BITCAST [[LOAD]](<4 x s64>)
+  ; CHECK:   [[UV2:%[0-9]+]]:_(<2 x p0>), [[UV3:%[0-9]+]]:_(<2 x p0>) = G_UNMERGE_VALUES %val_2(<4 x p0>)
+  ; CHECK: bb.2:
+  ; CHECK:   [[PHI:%[0-9]+]]:_(<2 x p0>) = G_PHI [[UV2]](<2 x p0>), %bb.1, [[UV]](<2 x p0>), %bb.0
+  ; CHECK:   [[PHI1:%[0-9]+]]:_(<2 x p0>) = G_PHI [[UV3]](<2 x p0>), %bb.1, [[UV1]](<2 x p0>), %bb.0
+  ; CHECK:   %phi:_(<4 x p0>) = G_CONCAT_VECTORS [[PHI]](<2 x p0>), [[PHI1]](<2 x p0>)
+  ; CHECK:   %unmerge_1:_(<2 x p0>), %unmerge_2:_(<2 x p0>) = G_UNMERGE_VALUES %phi(<4 x p0>)
+  ; CHECK:   $q0 = COPY %unmerge_1(<2 x p0>)
+  ; CHECK:   $q1 = COPY %unmerge_2(<2 x p0>)
+  ; CHECK:   RET_ReallyLR implicit $q0, implicit $q1
+  bb.0:
+    successors: %bb.1(0x50000000), %bb.2(0x30000000)
+    liveins: $x0, $x1
+
+    %ptr1:_(p0) = COPY $x1
+    %ptr2:_(p0) = COPY $x0
+    %cond:_(s1) = G_IMPLICIT_DEF
+    %val_1:_(<4 x p0>) = G_LOAD %ptr1(p0) :: (load (<4 x p0>))
+    G_BRCOND %cond(s1), %bb.2
+    G_BR %bb.1
+  bb.1:
+    %val_2:_(<4 x p0>) = G_LOAD %ptr2(p0) :: (load (<4 x p0>))
+  bb.2:
+    %phi:_(<4 x p0>) = G_PHI %val_2(<4 x p0>), %bb.1, %val_1(<4 x p0>), %bb.0
+    %unmerge_1:_(<2 x p0>), %unmerge_2:_(<2 x p0>) = G_UNMERGE_VALUES %phi(<4 x p0>)
+    $q0 = COPY %unmerge_1(<2 x p0>)
+    $q1 = COPY %unmerge_2(<2 x p0>)
+    RET_ReallyLR implicit $q0, implicit $q1