Index: lib/CodeGen/GlobalISel/LegalizerInfo.cpp
===================================================================
--- lib/CodeGen/GlobalISel/LegalizerInfo.cpp
+++ lib/CodeGen/GlobalISel/LegalizerInfo.cpp
@@ -75,8 +75,11 @@
 
   // Nothing is going to go well with types that aren't a power of 2 yet, so
   // don't even try because we might make things worse.
-  if (!isPowerOf2_64(Aspect.Type.getSizeInBits()))
-      return std::make_pair(Unsupported, LLT());
+  LLT Ty = Aspect.Type;
+  unsigned SizeInBits =
+      Ty.isVector() ? Ty.getElementType().getSizeInBits() : Ty.getSizeInBits();
+  if (!isPowerOf2_64(SizeInBits))
+    return std::make_pair(Unsupported, LLT());
 
   // FIXME: the long-term plan calls for expansion in terms of load/store (if
   // they're not legal).
@@ -91,7 +94,6 @@
     return findLegalAction(Aspect, Action);
 
   unsigned Opcode = Aspect.Opcode;
-  LLT Ty = Aspect.Type;
   if (!Ty.isVector()) {
     auto DefaultAction = DefaultActions.find(Aspect.Opcode);
     if (DefaultAction != DefaultActions.end() && DefaultAction->second == Legal)
Index: test/CodeGen/AArch64/GlobalISel/legalize-nonpowerof2eltsvec.mir
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/GlobalISel/legalize-nonpowerof2eltsvec.mir
@@ -0,0 +1,29 @@
+# RUN: llc -O0 -run-pass=legalizer -global-isel %s -o - | FileCheck %s
+
+--- |
+  target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
+  target triple = "aarch64--"
+  define void @test_legalize_merge_v3s32() {
+    ret void
+  }
+...
+---
+name:            test_legalize_merge_v3s32
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+  - { id: 3, class: _ }
+body: |
+  bb.0:
+    liveins: %w0, %w1, %w2
+    ; CHECK-LABEL: name: test_legalize_merge_v3s32
+    ; CHECK: [[ARG1:%[0-9]+]](s32) = COPY %w0
+    ; CHECK: [[ARG2:%[0-9]+]](s32) = COPY %w1
+    ; CHECK: [[ARG3:%[0-9]+]](s32) = COPY %w2
+    ; CHECK: (<3 x s32>) = G_MERGE_VALUES [[ARG1]](s32), [[ARG2]](s32), [[ARG3]](s32)
+    %0(s32) = COPY %w0
+    %1(s32) = COPY %w1
+    %2(s32) = COPY %w2
+    %3(<3 x s32>) = G_MERGE_VALUES %0(s32), %1(s32), %2(s32)
+...