Index: llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
+++ llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
@@ -181,8 +181,15 @@
 void DwarfExpression::addUnsignedConstant(uint64_t Value) {
   assert(LocationKind == Implicit || LocationKind == Unknown);
   LocationKind = Implicit;
-  emitOp(dwarf::DW_OP_constu);
-  emitUnsigned(Value);
+  if (Value < 32)
+   emitOp(dwarf::DW_OP_lit0 + Value);
+  else if (Value == 0xfffffff) {
+   emitOp(dwarf::DW_OP_lit0);
+   emitOp(dwarf::DW_OP_not);
+  } else {
+   emitOp(dwarf::DW_OP_constu);
+   emitUnsigned(Value);
+  }
 }
 
 void DwarfExpression::addUnsignedConstant(const APInt &Value) {
Index: llvm/test/DebugInfo/ARM/PR26163.ll
===================================================================
--- llvm/test/DebugInfo/ARM/PR26163.ll
+++ llvm/test/DebugInfo/ARM/PR26163.ll
@@ -9,8 +9,8 @@
 ; CHECK: DW_TAG_inlined_subroutine
 ; CHECK: DW_TAG_variable
 ; CHECK:   DW_AT_location [DW_FORM_sec_offset] ({{.*}}
-; CHECK:      [0x00000004, 0x00000004): DW_OP_constu 0x0, DW_OP_stack_value, DW_OP_piece 0x8
-; CHECK:      [0x00000004, 0x00000014): DW_OP_constu 0x0, DW_OP_stack_value, DW_OP_piece 0x4)
+; CHECK:      [0x00000004, 0x00000004): DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x8
+; CHECK:      [0x00000004, 0x00000014): DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x4)
 
 ; Created form the following test case (PR26163) with
 ; clang -cc1 -triple armv4t--freebsd11.0-gnueabi -emit-obj -debug-info-kind=standalone -O2 -x c test.c
Index: llvm/test/DebugInfo/ARM/split-complex.ll
===================================================================
--- llvm/test/DebugInfo/ARM/split-complex.ll
+++ llvm/test/DebugInfo/ARM/split-complex.ll
@@ -14,7 +14,7 @@
   ; The target has no native double type.
   ; SROA split the complex value into two i64 values.
   ; CHECK: DW_TAG_formal_parameter
-  ; CHECK-NEXT:  DW_AT_location [DW_FORM_block1]	(DW_OP_constu 0x0, DW_OP_piece 0x8)
+  ; CHECK-NEXT:  DW_AT_location [DW_FORM_block1]	(DW_OP_lit0, DW_OP_piece 0x8)
   ; CHECK-NEXT:  DW_AT_name {{.*}} "c"
   tail call void @llvm.dbg.value(metadata i64 0, metadata !14, metadata !17), !dbg !16
   ; Manually removed to disable location list emission:
Index: llvm/test/DebugInfo/Generic/incorrect-variable-debugloc1.ll
===================================================================
--- llvm/test/DebugInfo/Generic/incorrect-variable-debugloc1.ll
+++ llvm/test/DebugInfo/Generic/incorrect-variable-debugloc1.ll
@@ -1,6 +1,6 @@
 ; REQUIRES: object-emission
 ; This test is failing for powerpc64, because a location list for the
-; variable 'c' is not generated at all. Temporary marking this test as XFAIL 
+; variable 'c' is not generated at all. Temporary marking this test as XFAIL
 ; for powerpc, until PR21881 is fixed.
 ; XFAIL: powerpc64
 
@@ -9,13 +9,14 @@
 ; RUN: %llc_dwarf -O2  -dwarf-version 4 -filetype=obj < %s | llvm-dwarfdump - | FileCheck %s  --check-prefix=DWARF4
 
 ; This is a test for PR21176.
-; DW_OP_const <const> doesn't describe a constant value, but a value at a constant address. 
+; DW_OP_const <const> doesn't describe a constant value, but a value at a constant address.
 ; The proper way to describe a constant value is DW_OP_constu <const>, DW_OP_stack_value.
+; For values < 32 we emit the canonical DW_OP_lit<const>.
 
 ; Generated with clang -S -emit-llvm -g -O2 test.cpp
 
 ; extern int func();
-; 
+;
 ; int main()
 ; {
 ;   volatile int c = 13;
@@ -26,8 +27,8 @@
 ; CHECK: DW_TAG_variable
 ; CHECK: DW_AT_location
 ; CHECK-NOT: DW_AT
-; DWARF23: DW_OP_constu 0xd{{$}}
-; DWARF4: DW_OP_constu 0xd, DW_OP_stack_value{{$}}
+; DWARF23: DW_OP_lit13{{$}}
+; DWARF4: DW_OP_lit13, DW_OP_stack_value{{$}}
 
 ; Function Attrs: uwtable
 define i32 @main() #0 !dbg !4 {
Index: llvm/test/DebugInfo/X86/PR26148.ll
===================================================================
--- llvm/test/DebugInfo/X86/PR26148.ll
+++ llvm/test/DebugInfo/X86/PR26148.ll
@@ -19,8 +19,8 @@
 ; AS in 26163, we expect two ranges (as opposed to one), the first one being zero sized
 ;
 ;
-; CHECK: [0x0000000000000004, 0x0000000000000004): DW_OP_constu 0x3, DW_OP_piece 0x4, DW_OP_reg5 RDI, DW_OP_piece 0x2
-; CHECK: [0x0000000000000004, 0x0000000000000014): DW_OP_constu 0x3, DW_OP_piece 0x4, DW_OP_constu 0x0, DW_OP_piece 0x4
+; CHECK: [0x0000000000000004, 0x0000000000000004): DW_OP_lit3, DW_OP_piece 0x4, DW_OP_reg5 RDI, DW_OP_piece 0x2
+; CHECK: [0x0000000000000004, 0x0000000000000014): DW_OP_lit3, DW_OP_piece 0x4, DW_OP_lit0, DW_OP_piece 0x4
 
 source_filename = "test/DebugInfo/X86/PR26148.ll"
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
Index: llvm/test/DebugInfo/X86/constant-loclist.ll
===================================================================
--- llvm/test/DebugInfo/X86/constant-loclist.ll
+++ llvm/test/DebugInfo/X86/constant-loclist.ll
@@ -14,7 +14,7 @@
 ; CHECK-NEXT: DW_AT_name {{.*}}"i"
 ; CHECK: DW_TAG_variable
 ; CHECK-NEXT: DW_AT_location [DW_FORM_data4]	(
-; CHECK-NEXT:   [0x{{.*}}, 0x{{.*}}): DW_OP_constu 0x0
+; CHECK-NEXT:   [0x{{.*}}, 0x{{.*}}): DW_OP_lit0
 ; CHECK-NEXT:   [0x{{.*}}, 0x{{.*}}): DW_OP_constu 0x4000000000000000)
 ; CHECK-NEXT: DW_AT_name {{.*}}"u"
 
Index: llvm/test/DebugInfo/X86/partial-constant.ll
===================================================================
--- llvm/test/DebugInfo/X86/partial-constant.ll
+++ llvm/test/DebugInfo/X86/partial-constant.ll
@@ -18,7 +18,7 @@
 ; CHECK-NOT: DW_AT_const_value
 ; CHECK: .debug_loc contents:
 ; CHECK-NEXT: 0x00000000:
-; CHECK-NEXT:   {{.*}}: DW_OP_constu 0x1, DW_OP_stack_value
+; CHECK-NEXT:   {{.*}}: DW_OP_lit1, DW_OP_stack_value
 
 source_filename = "test.ii"
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
Index: llvm/test/DebugInfo/X86/pieces-4.ll
===================================================================
--- llvm/test/DebugInfo/X86/pieces-4.ll
+++ llvm/test/DebugInfo/X86/pieces-4.ll
@@ -25,7 +25,7 @@
 
 ; DWARF: .debug_loc contents:
 ; DWARF-NEXT: 0x00000000:
-; DWARF-NEXT: {{.*}}: DW_OP_breg7 RSP+{{[0-9]+}}, DW_OP_piece 0x4, DW_OP_constu 0x0, DW_OP_stack_value, DW_OP_piece 0x4
+; DWARF-NEXT: {{.*}}: DW_OP_breg7 RSP+{{[0-9]+}}, DW_OP_piece 0x4, DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x4
 
 ; ModuleID = 't.c'
 source_filename = "t.c"
Index: llvm/test/DebugInfo/X86/stack-value-piece.ll
===================================================================
--- llvm/test/DebugInfo/X86/stack-value-piece.ll
+++ llvm/test/DebugInfo/X86/stack-value-piece.ll
@@ -19,21 +19,21 @@
 ; CHECK:   DW_AT_name {{.*}} "i"
 ; CHECK:   DW_TAG_variable
 ; CHECK-NEXT:   DW_AT_location {{.*}} ([[I:.*]]
-; CHECK-NEXT:     [{{.*}}, {{.*}}): DW_OP_reg5 RDI, DW_OP_piece 0x4, DW_OP_constu 0x0, DW_OP_stack_value, DW_OP_piece 0x4)
+; CHECK-NEXT:     [{{.*}}, {{.*}}): DW_OP_reg5 RDI, DW_OP_piece 0x4, DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x4)
 ; CHECK-NEXT:   DW_AT_name {{.*}} "r"
 ;
 ; CHECK: DW_TAG_subprogram
 ; CHECK:   DW_AT_name {{.*}} "f"
 ; CHECK:   DW_TAG_variable
 ; CHECK-NEXT:   DW_AT_location {{.*}} ([[F:.*]]
-; CHECK-NEXT:     [{{.*}}, {{.*}}): DW_OP_reg17 XMM0, DW_OP_piece 0x4, DW_OP_constu 0x0, DW_OP_stack_value, DW_OP_piece 0x4)
+; CHECK-NEXT:     [{{.*}}, {{.*}}): DW_OP_reg17 XMM0, DW_OP_piece 0x4, DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x4)
 ; CHECK-NEXT:   DW_AT_name {{.*}} "r"
 ;
 ; CHECK: .debug_loc contents:
 ; CHECK:      [[I]]:
-; CHECK-NEXT:   [{{.*}}, {{.*}}): DW_OP_reg5 RDI, DW_OP_piece 0x4, DW_OP_constu 0x0, DW_OP_stack_value, DW_OP_piece 0x4
+; CHECK-NEXT:   [{{.*}}, {{.*}}): DW_OP_reg5 RDI, DW_OP_piece 0x4, DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x4
 ; CHECK:      [[F]]:
-; CHECK-NEXT:   [{{.*}}, {{.*}}): DW_OP_reg17 XMM0, DW_OP_piece 0x4, DW_OP_constu 0x0, DW_OP_stack_value, DW_OP_piece 0x4
+; CHECK-NEXT:   [{{.*}}, {{.*}}): DW_OP_reg17 XMM0, DW_OP_piece 0x4, DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x4
 
 source_filename = "stack-value-piece.c"
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"