diff --git a/llvm/include/llvm/MC/LaneBitmask.h b/llvm/include/llvm/MC/LaneBitmask.h
index d5f69287a265b..b070bea3201cf 100644
--- a/llvm/include/llvm/MC/LaneBitmask.h
+++ b/llvm/include/llvm/MC/LaneBitmask.h
@@ -38,9 +38,9 @@ namespace llvm {
 
   struct LaneBitmask {
     // When changing the underlying type, change the format string as well.
-    using Type = unsigned;
+    using Type = uint64_t;
     enum : unsigned { BitWidth = 8*sizeof(Type) };
-    constexpr static const char *const FormatStr = "%08X";
+    constexpr static const char *const FormatStr = "%016lX";
 
     constexpr LaneBitmask() = default;
     explicit constexpr LaneBitmask(Type V) : Mask(V) {}
@@ -76,7 +76,7 @@ namespace llvm {
       return countPopulation(Mask);
     }
     unsigned getHighestLane() const {
-      return Log2_32(Mask);
+      return Log2_64(Mask);
     }
 
     static constexpr LaneBitmask getNone() { return LaneBitmask(0); }
diff --git a/llvm/lib/CodeGen/MIRParser/MIParser.cpp b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
index 2a220c02613c8..c20c1552377dc 100644
--- a/llvm/lib/CodeGen/MIRParser/MIParser.cpp
+++ b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
@@ -750,10 +750,10 @@ bool MIParser::parseBasicBlockLiveins(MachineBasicBlock &MBB) {
       if (Token.isNot(MIToken::IntegerLiteral) &&
           Token.isNot(MIToken::HexLiteral))
         return error("expected a lane mask");
-      static_assert(sizeof(LaneBitmask::Type) == sizeof(unsigned),
+      static_assert(sizeof(LaneBitmask::Type) == sizeof(uint64_t),
                     "Use correct get-function for lane mask");
       LaneBitmask::Type V;
-      if (getUnsigned(V))
+      if (getUint64(V))
         return error("invalid lane mask value");
       Mask = LaneBitmask(V);
       lex();
diff --git a/llvm/test/CodeGen/AMDGPU/at-least-one-def-value-assert.mir b/llvm/test/CodeGen/AMDGPU/at-least-one-def-value-assert.mir
index eb244190e562e..4503ed12cb6fb 100644
--- a/llvm/test/CodeGen/AMDGPU/at-least-one-def-value-assert.mir
+++ b/llvm/test/CodeGen/AMDGPU/at-least-one-def-value-assert.mir
@@ -5,7 +5,7 @@
 # CHECK-NEXT: - basic block: %bb.0
 # CHECK-NEXT: - instruction: 48B	dead undef %2.sub0:vreg_128 = COPY %0.sub0:vreg_128
 # CHECK-NEXT: - operand 1:   %0.sub0:vreg_128
-# CHECK-NEXT: - interval:    %0 [16r,48r:0)  0@16r L00000002 [16r,32r:0)  0@16r weight:0.000000e+00
+# CHECK-NEXT: - interval:    %0 [16r,48r:0)  0@16r L0000000000000002 [16r,32r:0)  0@16r weight:0.000000e+00
 
 # This used to assert with: !SR.empty() && "At least one value should be defined by this mask"
 
diff --git a/llvm/test/CodeGen/AMDGPU/postra-machine-sink.mir b/llvm/test/CodeGen/AMDGPU/postra-machine-sink.mir
index b034cae992608..c77d6e0eb1be1 100644
--- a/llvm/test/CodeGen/AMDGPU/postra-machine-sink.mir
+++ b/llvm/test/CodeGen/AMDGPU/postra-machine-sink.mir
@@ -5,7 +5,7 @@
 # CHECK-LABEL: bb.0:
 # CHECK: renamable $sgpr1 = COPY renamable $sgpr2
 # CHECK-LABEL: bb.1:
-# CHECK: liveins: $sgpr0_sgpr1:0x00000003
+# CHECK: liveins: $sgpr0_sgpr1:0x0000000000000003
 # CHECK: renamable $vgpr1_vgpr2 = COPY renamable $sgpr0_sgpr1
 
 ---
diff --git a/llvm/test/CodeGen/Hexagon/verify-liveness-at-def.mir b/llvm/test/CodeGen/Hexagon/verify-liveness-at-def.mir
index fefe245140990..d57325e5b27db 100644
--- a/llvm/test/CodeGen/Hexagon/verify-liveness-at-def.mir
+++ b/llvm/test/CodeGen/Hexagon/verify-liveness-at-def.mir
@@ -40,21 +40,21 @@ body: |
 # CHECK-SUB: Bad machine code: Live range continues after dead def flag
 # CHECK_SUB-NEXT: function:    test_fail
 # CHECK-SUB:      v. register: %0
-# CHECK-SUB:      lanemask:    00000002
+# CHECK-SUB:      lanemask:    0000000000000002
 #
 # CHECK-SUB-NOT: Bad machine code
 #
 # CHECK-SUB: Bad machine code: Live range continues after dead def flag
 # CHECK-SUB-NEXT: function:    test_fail
 # CHECK-SUB:      v. register: %1
-# CHECK-SUB:      lanemask:    00000002
+# CHECK-SUB:      lanemask:    0000000000000002
 #
 # CHECK-SUB-NOT: Bad machine code
 #
 # CHECK-SUB: Bad machine code: Live range continues after dead def flag
 # CHECK-SUB-NEXT: function:    test_fail
 # CHECK-SUB:      v. register: %1
-# CHECK-SUB:      lanemask:    00000001
+# CHECK-SUB:      lanemask:    0000000000000001
 #
 # CHECK-SUB: Bad machine code: Live range continues after dead def flag
 # CHECK-SUB-NEXT: function:    test_fail
diff --git a/llvm/test/CodeGen/MIR/Hexagon/parse-lane-masks.mir b/llvm/test/CodeGen/MIR/Hexagon/parse-lane-masks.mir
index 1b6dc3b4c41bf..915c354b5a0ff 100644
--- a/llvm/test/CodeGen/MIR/Hexagon/parse-lane-masks.mir
+++ b/llvm/test/CodeGen/MIR/Hexagon/parse-lane-masks.mir
@@ -3,7 +3,7 @@
 
 # CHECK-LABEL: name: foo
 # CHECK: bb.0:
-# CHECK: liveins: $d0:0x00000002, $d1, $d2:0x00000010
+# CHECK: liveins: $d0:0x0000000000000002, $d1, $d2:0x0000000000000010
 
 --- |
   define void @foo() {