diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -4950,7 +4950,8 @@
     Observer.changedInstr(MI);
     return Legalized;
   }
-  case TargetOpcode::G_FPTRUNC: {
+  case TargetOpcode::G_FPTRUNC:
+  case TargetOpcode::G_FPEXT: {
     if (TypeIdx != 0)
       return UnableToLegalize;
     Observer.changingInstr(MI);
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
--- a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
@@ -541,7 +541,9 @@
   getActionDefinitionsBuilder(G_FPEXT)
       .legalFor(
           {{s32, s16}, {s64, s16}, {s64, s32}, {v4s32, v4s16}, {v2s64, v2s32}})
-      .clampMaxNumElements(0, s64, 2);
+      .clampNumElements(0, v4s32, v4s32)
+      .clampNumElements(0, v2s64, v2s64)
+      .scalarize(0);
 
   // Conversions
   getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
diff --git a/llvm/test/CodeGen/AArch64/fpext.ll b/llvm/test/CodeGen/AArch64/fpext.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/fpext.ll
@@ -0,0 +1,234 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 3
+; RUN: llc -mtriple=aarch64-none-eabi -global-isel=0 -verify-machineinstrs %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-SD
+; RUN: llc -mtriple=aarch64-none-eabi -global-isel=1 -verify-machineinstrs %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-GI
+
+define double @fpext_f32_f64(float %a) {
+; CHECK-LABEL: fpext_f32_f64:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvt d0, s0
+; CHECK-NEXT:    ret
+entry:
+  %c = fpext float %a to double
+  ret double %c
+}
+
+define double @fpext_f16_f64(half %a) {
+; CHECK-LABEL: fpext_f16_f64:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvt d0, h0
+; CHECK-NEXT:    ret
+entry:
+  %c = fpext half %a to double
+  ret double %c
+}
+
+define float @fpext_f16_f32(half %a) {
+; CHECK-LABEL: fpext_f16_f32:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvt s0, h0
+; CHECK-NEXT:    ret
+entry:
+  %c = fpext half %a to float
+  ret float %c
+}
+
+define <2 x double> @fpext_v2f32_v2f64(<2 x float> %a) {
+; CHECK-LABEL: fpext_v2f32_v2f64:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvtl v0.2d, v0.2s
+; CHECK-NEXT:    ret
+entry:
+  %c = fpext <2 x float> %a to <2 x double>
+  ret <2 x double> %c
+}
+
+define <3 x double> @fpext_v3f32_v3f64(<3 x float> %a) {
+; CHECK-SD-LABEL: fpext_v3f32_v3f64:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    fcvtl v3.2d, v0.2s
+; CHECK-SD-NEXT:    fcvtl2 v2.2d, v0.4s
+; CHECK-SD-NEXT:    // kill: def $d2 killed $d2 killed $q2
+; CHECK-SD-NEXT:    fmov d0, d3
+; CHECK-SD-NEXT:    ext v1.16b, v3.16b, v3.16b, #8
+; CHECK-SD-NEXT:    // kill: def $d1 killed $d1 killed $q1
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fpext_v3f32_v3f64:
+; CHECK-GI:       // %bb.0: // %entry
+; CHECK-GI-NEXT:    mov s1, v0.s[2]
+; CHECK-GI-NEXT:    fcvtl v0.2d, v0.2s
+; CHECK-GI-NEXT:    fcvt d2, s1
+; CHECK-GI-NEXT:    mov d1, v0.d[1]
+; CHECK-GI-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fpext <3 x float> %a to <3 x double>
+  ret <3 x double> %c
+}
+
+define <4 x double> @fpext_v4f32_v4f64(<4 x float> %a) {
+; CHECK-SD-LABEL: fpext_v4f32_v4f64:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    fcvtl2 v1.2d, v0.4s
+; CHECK-SD-NEXT:    fcvtl v0.2d, v0.2s
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fpext_v4f32_v4f64:
+; CHECK-GI:       // %bb.0: // %entry
+; CHECK-GI-NEXT:    mov d1, v0.d[1]
+; CHECK-GI-NEXT:    fcvtl v0.2d, v0.2s
+; CHECK-GI-NEXT:    fcvtl v1.2d, v1.2s
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fpext <4 x float> %a to <4 x double>
+  ret <4 x double> %c
+}
+
+define <2 x double> @fpext_v2f16_v2f64(<2 x half> %a) {
+; CHECK-SD-LABEL: fpext_v2f16_v2f64:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    // kill: def $d0 killed $d0 def $q0
+; CHECK-SD-NEXT:    mov h1, v0.h[1]
+; CHECK-SD-NEXT:    fcvt d0, h0
+; CHECK-SD-NEXT:    fcvt d1, h1
+; CHECK-SD-NEXT:    mov v0.d[1], v1.d[0]
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fpext_v2f16_v2f64:
+; CHECK-GI:       // %bb.0: // %entry
+; CHECK-GI-NEXT:    fmov x8, d0
+; CHECK-GI-NEXT:    fmov s0, w8
+; CHECK-GI-NEXT:    mov h1, v0.h[1]
+; CHECK-GI-NEXT:    fcvt d0, h0
+; CHECK-GI-NEXT:    fcvt d1, h1
+; CHECK-GI-NEXT:    mov v0.d[1], v1.d[0]
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fpext <2 x half> %a to <2 x double>
+  ret <2 x double> %c
+}
+
+define <3 x double> @fpext_v3f16_v3f64(<3 x half> %a) {
+; CHECK-LABEL: fpext_v3f16_v3f64:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    // kill: def $d0 killed $d0 def $q0
+; CHECK-NEXT:    mov h1, v0.h[1]
+; CHECK-NEXT:    mov h2, v0.h[2]
+; CHECK-NEXT:    fcvt d0, h0
+; CHECK-NEXT:    fcvt d1, h1
+; CHECK-NEXT:    fcvt d2, h2
+; CHECK-NEXT:    ret
+entry:
+  %c = fpext <3 x half> %a to <3 x double>
+  ret <3 x double> %c
+}
+
+define <4 x double> @fpext_v4f16_v4f64(<4 x half> %a) {
+; CHECK-SD-LABEL: fpext_v4f16_v4f64:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    // kill: def $d0 killed $d0 def $q0
+; CHECK-SD-NEXT:    mov h1, v0.h[1]
+; CHECK-SD-NEXT:    mov h2, v0.h[3]
+; CHECK-SD-NEXT:    mov h3, v0.h[2]
+; CHECK-SD-NEXT:    fcvt d0, h0
+; CHECK-SD-NEXT:    fcvt d4, h1
+; CHECK-SD-NEXT:    fcvt d2, h2
+; CHECK-SD-NEXT:    fcvt d1, h3
+; CHECK-SD-NEXT:    mov v0.d[1], v4.d[0]
+; CHECK-SD-NEXT:    mov v1.d[1], v2.d[0]
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fpext_v4f16_v4f64:
+; 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 h2, v0.h[1]
+; CHECK-GI-NEXT:    fcvt d0, h0
+; CHECK-GI-NEXT:    mov h3, v1.h[1]
+; CHECK-GI-NEXT:    fcvt d2, h2
+; CHECK-GI-NEXT:    fcvt d1, h1
+; CHECK-GI-NEXT:    fcvt d3, h3
+; CHECK-GI-NEXT:    mov v0.d[1], v2.d[0]
+; CHECK-GI-NEXT:    mov v1.d[1], v3.d[0]
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fpext <4 x half> %a to <4 x double>
+  ret <4 x double> %c
+}
+
+define <2 x float> @fpext_v2f16_v2f32(<2 x half> %a) {
+; CHECK-SD-LABEL: fpext_v2f16_v2f32:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    fcvtl v0.4s, v0.4h
+; CHECK-SD-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fpext_v2f16_v2f32:
+; CHECK-GI:       // %bb.0: // %entry
+; CHECK-GI-NEXT:    fmov x8, d0
+; CHECK-GI-NEXT:    fmov s0, w8
+; 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:    fcvtl v0.4s, v0.4h
+; CHECK-GI-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fpext <2 x half> %a to <2 x float>
+  ret <2 x float> %c
+}
+
+define <3 x float> @fpext_v3f16_v3f32(<3 x half> %a) {
+; CHECK-SD-LABEL: fpext_v3f16_v3f32:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    fcvtl v0.4s, v0.4h
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fpext_v3f16_v3f32:
+; CHECK-GI:       // %bb.0: // %entry
+; CHECK-GI-NEXT:    // kill: def $d0 killed $d0 def $q0
+; CHECK-GI-NEXT:    mov h1, v0.h[1]
+; CHECK-GI-NEXT:    mov h2, v0.h[2]
+; CHECK-GI-NEXT:    mov v0.h[1], v1.h[0]
+; CHECK-GI-NEXT:    mov v0.h[2], v2.h[0]
+; CHECK-GI-NEXT:    mov v0.h[3], v0.h[0]
+; CHECK-GI-NEXT:    fcvtl v0.4s, v0.4h
+; CHECK-GI-NEXT:    mov s1, v0.s[1]
+; CHECK-GI-NEXT:    mov s2, v0.s[2]
+; CHECK-GI-NEXT:    mov v0.s[1], v1.s[0]
+; CHECK-GI-NEXT:    mov v0.s[2], v2.s[0]
+; CHECK-GI-NEXT:    mov v0.s[3], v0.s[0]
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fpext <3 x half> %a to <3 x float>
+  ret <3 x float> %c
+}
+
+define <4 x float> @fpext_v4f16_v4f32(<4 x half> %a) {
+; CHECK-LABEL: fpext_v4f16_v4f32:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fcvtl v0.4s, v0.4h
+; CHECK-NEXT:    ret
+entry:
+  %c = fpext <4 x half> %a to <4 x float>
+  ret <4 x float> %c
+}
+
+define <8 x float> @fpext_v8f16_v8f32(<8 x half> %a) {
+; CHECK-SD-LABEL: fpext_v8f16_v8f32:
+; CHECK-SD:       // %bb.0: // %entry
+; CHECK-SD-NEXT:    fcvtl2 v1.4s, v0.8h
+; CHECK-SD-NEXT:    fcvtl v0.4s, v0.4h
+; CHECK-SD-NEXT:    ret
+;
+; CHECK-GI-LABEL: fpext_v8f16_v8f32:
+; CHECK-GI:       // %bb.0: // %entry
+; CHECK-GI-NEXT:    mov d1, v0.d[1]
+; CHECK-GI-NEXT:    fcvtl v0.4s, v0.4h
+; CHECK-GI-NEXT:    fcvtl v1.4s, v1.4h
+; CHECK-GI-NEXT:    ret
+entry:
+  %c = fpext <8 x half> %a to <8 x float>
+  ret <8 x float> %c
+}