Index: llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
===================================================================
--- llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -4950,6 +4950,18 @@
     Observer.changedInstr(MI);
     return Legalized;
   }
+  case TargetOpcode::G_FPTRUNC: {
+    if (TypeIdx != 0)
+      return UnableToLegalize;
+    Observer.changingInstr(MI);
+    LLT SrcTy = LLT::fixed_vector(
+        MoreTy.getNumElements(),
+        MRI.getType(MI.getOperand(1).getReg()).getElementType());
+    moreElementsVectorSrc(MI, SrcTy, 1);
+    moreElementsVectorDst(MI, MoreTy, 0);
+    Observer.changedInstr(MI);
+    return Legalized;
+  }
   default:
     return UnableToLegalize;
   }
Index: llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
===================================================================
--- llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
+++ llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
@@ -534,7 +534,10 @@
   getActionDefinitionsBuilder(G_FPTRUNC)
       .legalFor(
           {{s16, s32}, {s16, s64}, {s32, s64}, {v4s16, v4s32}, {v2s32, v2s64}})
-      .clampMaxNumElements(0, s32, 2);
+      .clampNumElements(0, v4s16, v4s16)
+      .clampNumElements(0, v2s32, v2s32)
+      .scalarize(0);
+
   getActionDefinitionsBuilder(G_FPEXT)
       .legalFor(
           {{s32, s16}, {s64, s16}, {s64, s32}, {v4s32, v4s16}, {v2s64, v2s32}})
Index: llvm/test/CodeGen/AArch64/GlobalISel/legalize-fptrunc.mir
===================================================================
--- llvm/test/CodeGen/AArch64/GlobalISel/legalize-fptrunc.mir
+++ llvm/test/CodeGen/AArch64/GlobalISel/legalize-fptrunc.mir
@@ -82,8 +82,12 @@
     ; CHECK: liveins: $d0
     ; CHECK-NEXT: {{  $}}
     ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<2 x s32>) = COPY $d0
-    ; CHECK-NEXT: [[FPTRUNC:%[0-9]+]]:_(<2 x s16>) = G_FPTRUNC [[COPY]](<2 x s32>)
-    ; CHECK-NEXT: $s0 = COPY [[FPTRUNC]](<2 x s16>)
+    ; CHECK-NEXT: [[UV:%[0-9]+]]:_(s32), [[UV1:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[COPY]](<2 x s32>)
+    ; CHECK-NEXT: [[DEF:%[0-9]+]]:_(s32) = G_IMPLICIT_DEF
+    ; CHECK-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<4 x s32>) = G_BUILD_VECTOR [[UV]](s32), [[UV1]](s32), [[DEF]](s32), [[DEF]](s32)
+    ; CHECK-NEXT: [[FPTRUNC:%[0-9]+]]:_(<4 x s16>) = G_FPTRUNC [[BUILD_VECTOR]](<4 x s32>)
+    ; CHECK-NEXT: [[UV2:%[0-9]+]]:_(<2 x s16>), [[UV3:%[0-9]+]]:_(<2 x s16>) = G_UNMERGE_VALUES [[FPTRUNC]](<4 x s16>)
+    ; CHECK-NEXT: $s0 = COPY [[UV2]](<2 x s16>)
     ; CHECK-NEXT: RET_ReallyLR implicit $s0
     %0:_(<2 x s32>) = COPY $d0
     %1:_(<2 x s16>) = G_FPTRUNC %0
Index: llvm/test/CodeGen/AArch64/fptrunc.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/fptrunc.ll
@@ -0,0 +1,159 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc -mtriple=aarch64-none-eabi -verify-machineinstrs %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-SD
+; RUN: llc -mtriple=aarch64-none-eabi -global-isel -verify-machineinstrs %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-GI
+
+define float @fptrunc_f64_f32(double %a) {
+; CHECK-LABEL: fptrunc_f64_f32:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvt s0, d0
+; CHECK-NEXT:    ret
+entry:
+  %c = fptrunc double %a to float
+  ret float %c
+}
+
+define half @fptrunc_f64_f16(double %a) {
+; CHECK-LABEL: fptrunc_f64_f16:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvt h0, d0
+; CHECK-NEXT:    ret
+entry:
+  %c = fptrunc double %a to half
+  ret half %c
+}
+
+define half @fptrunc_f32_f16(float %a) {
+; CHECK-LABEL: fptrunc_f32_f16:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvt h0, s0
+; CHECK-NEXT:    ret
+entry:
+  %c = fptrunc float %a to half
+  ret half %c
+}
+
+define <2 x float> @fptrunc_v2f64_v2f32(<2 x double> %a) {
+; CHECK-LABEL: fptrunc_v2f64_v2f32:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvtn v0.2s, v0.2d
+; CHECK-NEXT:    ret
+entry:
+  %c = fptrunc <2 x double> %a to <2 x float>
+  ret <2 x float> %c
+}
+
+define <4 x float> @fptrunc_v4f64_v4f32(<4 x double> %a) {
+; CHECK-LABEL: fptrunc_v4f64_v4f32:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvtn v0.2s, v0.2d
+; CHECK-NEXT:    fcvtn2 v0.4s, v1.2d
+; CHECK-NEXT:    ret
+entry:
+  %c = fptrunc <4 x double> %a to <4 x float>
+  ret <4 x float> %c
+}
+
+define <2 x half> @fptrunc_v2f64_v2f16(<2 x double> %a) {
+; CHECK-SD-LABEL: fptrunc_v2f64_v2f16:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    mov d1, v0.d[1]
+; CHECK-SD-NEXT:    fcvt h0, d0
+; CHECK-SD-NEXT:    fcvt h1, d1
+; CHECK-SD-NEXT:    mov v0.h[1], v1.h[0]
+; CHECK-SD-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fptrunc_v2f64_v2f16:
+; CHECK-GI:       // %bb.0: // %entry
+; CHECK-GI-NEXT:    mov d1, v0.d[1]
+; CHECK-GI-NEXT:    fcvt h0, d0
+; CHECK-GI-NEXT:    fcvt h1, d1
+; CHECK-GI-NEXT:    mov v0.h[1], v1.h[0]
+; CHECK-GI-NEXT:    mov v0.h[2], v0.h[0]
+; CHECK-GI-NEXT:    mov v0.h[3], v0.h[0]
+; CHECK-GI-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fptrunc <2 x double> %a to <2 x half>
+  ret <2 x half> %c
+}
+
+define <4 x half> @fptrunc_v4f64_v4f16(<4 x double> %a) {
+; CHECK-SD-LABEL: fptrunc_v4f64_v4f16:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    mov d2, v0.d[1]
+; CHECK-SD-NEXT:    fcvt h0, d0
+; CHECK-SD-NEXT:    fcvt h2, d2
+; CHECK-SD-NEXT:    mov v0.h[1], v2.h[0]
+; CHECK-SD-NEXT:    fcvt h2, d1
+; CHECK-SD-NEXT:    mov d1, v1.d[1]
+; CHECK-SD-NEXT:    mov v0.h[2], v2.h[0]
+; CHECK-SD-NEXT:    fcvt h1, d1
+; CHECK-SD-NEXT:    mov v0.h[3], v1.h[0]
+; CHECK-SD-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fptrunc_v4f64_v4f16:
+; CHECK-GI:       // %bb.0: // %entry
+; CHECK-GI-NEXT:    mov d2, v0.d[1]
+; CHECK-GI-NEXT:    fcvt h0, d0
+; CHECK-GI-NEXT:    mov d3, v1.d[1]
+; CHECK-GI-NEXT:    fcvt h1, d1
+; CHECK-GI-NEXT:    fcvt h2, d2
+; CHECK-GI-NEXT:    mov v0.h[1], v2.h[0]
+; CHECK-GI-NEXT:    fcvt h2, d3
+; CHECK-GI-NEXT:    mov v0.h[2], v1.h[0]
+; CHECK-GI-NEXT:    mov v0.h[3], v2.h[0]
+; CHECK-GI-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fptrunc <4 x double> %a to <4 x half>
+  ret <4 x half> %c
+}
+
+define <2 x half> @fptrunc_v2f32_v2f16(<2 x float> %a) {
+; CHECK-SD-LABEL: fptrunc_v2f32_v2f16:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    // kill: def $d0 killed $d0 def $q0
+; CHECK-SD-NEXT:    fcvtn v0.4h, v0.4s
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fptrunc_v2f32_v2f16:
+; CHECK-GI:       // %bb.0: // %entry
+; CHECK-GI-NEXT:    // kill: def $d0 killed $d0 def $q0
+; CHECK-GI-NEXT:    mov s1, v0.s[1]
+; CHECK-GI-NEXT:    mov v0.s[1], v1.s[0]
+; CHECK-GI-NEXT:    mov v0.s[2], v0.s[0]
+; CHECK-GI-NEXT:    mov v0.s[3], v0.s[0]
+; CHECK-GI-NEXT:    fcvtn v0.4h, v0.4s
+; CHECK-GI-NEXT:    mov h1, v0.h[1]
+; CHECK-GI-NEXT:    mov v0.h[1], v1.h[0]
+; CHECK-GI-NEXT:    mov v0.h[2], v0.h[0]
+; CHECK-GI-NEXT:    mov v0.h[3], v0.h[0]
+; CHECK-GI-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fptrunc <2 x float> %a to <2 x half>
+  ret <2 x half> %c
+}
+
+define <4 x half> @fptrunc_v4f32_v4f16(<4 x float> %a) {
+; CHECK-LABEL: fptrunc_v4f32_v4f16:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvtn v0.4h, v0.4s
+; CHECK-NEXT:    ret
+entry:
+  %c = fptrunc <4 x float> %a to <4 x half>
+  ret <4 x half> %c
+}
+
+define <8 x half> @fptrunc_v8f32_v8f16(<8 x float> %a) {
+; CHECK-LABEL: fptrunc_v8f32_v8f16:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvtn v0.4h, v0.4s
+; CHECK-NEXT:    fcvtn2 v0.8h, v1.4s
+; CHECK-NEXT:    ret
+entry:
+  %c = fptrunc <8 x float> %a to <8 x half>
+  ret <8 x half> %c
+}