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
@@ -757,6 +757,9 @@
       .libcallFor({s128})
       .minScalar(0, MinFPScalar);
 
+  // TODO: Libcall support for s128.
+  getActionDefinitionsBuilder(G_LROUND).legalFor({{s64, s32}, {s64, s64}});
+
   getLegacyLegalizerInfo().computeTables();
   verify(*ST.getInstrInfo());
 }
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/legalize-lround.mir b/llvm/test/CodeGen/AArch64/GlobalISel/legalize-lround.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/legalize-lround.mir
@@ -0,0 +1,39 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=aarch64 -run-pass=legalizer -verify-machineinstrs %s -o - | FileCheck %s
+
+...
+---
+name:            s64_s32_legal
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $s0
+    ; CHECK-LABEL: name: s64_s32_legal
+    ; CHECK: liveins: $s0
+    ; CHECK: %copy:_(s32) = COPY $s0
+    ; CHECK: %lround:_(s64) = G_LROUND %copy(s32)
+    ; CHECK: %trunc:_(s32) = G_TRUNC %lround(s64)
+    ; CHECK: $w0 = COPY %trunc(s32)
+    ; CHECK: RET_ReallyLR implicit $w0
+    %copy:_(s32) = COPY $s0
+    %lround:_(s64) = G_LROUND %copy(s32)
+    %trunc:_(s32) = G_TRUNC %lround
+    $w0 = COPY %trunc(s32)
+    RET_ReallyLR implicit $w0
+...
+---
+name:            s64_s64_legal
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $d0
+    ; CHECK-LABEL: name: s64_s64_legal
+    ; CHECK: liveins: $d0
+    ; CHECK: %copy:_(s64) = COPY $d0
+    ; CHECK: %lround:_(s64) = G_LROUND %copy(s64)
+    ; CHECK: $x0 = COPY %lround(s64)
+    ; CHECK: RET_ReallyLR implicit $x0
+    %copy:_(s64) = COPY $d0
+    %lround:_(s64) = G_LROUND %copy(s64)
+    $x0 = COPY %lround
+    RET_ReallyLR implicit $x0
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
--- a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
@@ -527,8 +527,8 @@
 # DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
 # DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
 # DEBUG-NEXT: G_LROUND (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
-# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
-# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. the first uncovered type index: 2, OK
+# DEBUG-NEXT: .. the first uncovered imm index: 0, OK
 # DEBUG-NEXT: G_LLROUND (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
 # DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
 # DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined