Index: llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
+++ llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -739,11 +739,39 @@
 int ARMTTIImpl::getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy,
                                    TTI::TargetCostKind CostKind,
                                    const Instruction *I) {
-  // TODO: Handle other cost kinds.
+  int ISD = TLI->InstructionOpcodeToISD(Opcode);
+
+  // Override cost kind at minsize.
+  if (ST->hasMinSize())
+    CostKind = TTI::TCK_CodeSize;
+
+  // Thumb scalar code size cost for select.
+  if (CostKind == TTI::TCK_CodeSize && ISD == ISD::SELECT &&
+      ST->isThumb() && !ValTy->isVectorTy()) {
+    // Assume expensive structs.
+    if (TLI->getValueType(DL, ValTy, true) == MVT::Other)
+      return TTI::TCC_Expensive;
+
+    // Select costs can vary because they:
+    // - may require one or more conditional mov (including an IT),
+    // - can't operate directly on immediates,
+    // - require live flags, which we can't copy around easily.
+    int Cost = TLI->getTypeLegalizationCost(DL, ValTy).first;
+
+    // Possible IT instruction for Thumb2, or more for Thumb1.
+    ++Cost;
+
+    // i1 values may need rematerialising by using mov immediates and/or
+    // flag setting instructions.
+    if (ValTy->isIntegerTy(1))
+      ++Cost;
+
+    return Cost;
+  }
+
   if (CostKind != TTI::TCK_RecipThroughput)
     return BaseT::getCmpSelInstrCost(Opcode, ValTy, CondTy, CostKind, I);
 
-  int ISD = TLI->InstructionOpcodeToISD(Opcode);
   // On NEON a vector select gets lowered to vbsl.
   if (ST->hasNEON() && ValTy->isVectorTy() && ISD == ISD::SELECT) {
     // Lowering of some vector selects is currently far from perfect.
Index: llvm/test/Analysis/CostModel/ARM/immediates.ll
===================================================================
--- llvm/test/Analysis/CostModel/ARM/immediates.ll
+++ llvm/test/Analysis/CostModel/ARM/immediates.ll
@@ -25,8 +25,8 @@
 ; CHECK-T1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %cmp_244 = icmp ne i32 undef, 244
 ; CHECK-T1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %cmp_256 = icmp uge i32 undef, 256
 ; CHECK-T1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %cmp_1024 = icmp ult i32 undef, 1024
-; CHECK-T1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %select_1_0 = select i1 undef, i32 1, i32 0
-; CHECK-T1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %select_7_255 = select i1 undef, i32 7, i32 255
+; CHECK-T1-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %select_1_0 = select i1 undef, i32 1, i32 0
+; CHECK-T1-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %select_7_255 = select i1 undef, i32 7, i32 255
 ; CHECK-T1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret i32 1
 ;
 ; CHECK-T2-SIZE-LABEL: 'const_costs'
@@ -47,8 +47,8 @@
 ; CHECK-T2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %cmp_244 = icmp ne i32 undef, 244
 ; CHECK-T2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %cmp_256 = icmp uge i32 undef, 256
 ; CHECK-T2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %cmp_1024 = icmp ult i32 undef, 1024
-; CHECK-T2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %select_1_0 = select i1 undef, i32 1, i32 0
-; CHECK-T2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %select_7_255 = select i1 undef, i32 7, i32 255
+; CHECK-T2-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %select_1_0 = select i1 undef, i32 1, i32 0
+; CHECK-T2-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %select_7_255 = select i1 undef, i32 7, i32 255
 ; CHECK-T2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret i32 1
 ;
 ; CHECK-T1-LATENCY-LABEL: 'const_costs'
Index: llvm/test/Analysis/CostModel/ARM/select.ll
===================================================================
--- llvm/test/Analysis/CostModel/ARM/select.ll
+++ llvm/test/Analysis/CostModel/ARM/select.ll
@@ -11,6 +11,7 @@
 define void @selects() {
   ; Scalar values
 ; CHECK-MVE-RECIP-LABEL: 'selects'
+; CHECK-MVE-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v0 = select i1 undef, i1 undef, i1 undef
 ; CHECK-MVE-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
 ; CHECK-MVE-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
 ; CHECK-MVE-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
@@ -42,6 +43,7 @@
 ; CHECK-MVE-RECIP-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret void
 ;
 ; CHECK-NEON-RECIP-LABEL: 'selects'
+; CHECK-NEON-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v0 = select i1 undef, i1 undef, i1 undef
 ; CHECK-NEON-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
 ; CHECK-NEON-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
 ; CHECK-NEON-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
@@ -73,6 +75,7 @@
 ; CHECK-NEON-RECIP-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret void
 ;
 ; CHECK-THUMB1-RECIP-LABEL: 'selects'
+; CHECK-THUMB1-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v0 = select i1 undef, i1 undef, i1 undef
 ; CHECK-THUMB1-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
 ; CHECK-THUMB1-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
 ; CHECK-THUMB1-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
@@ -104,6 +107,7 @@
 ; CHECK-THUMB1-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
 ; CHECK-THUMB2-RECIP-LABEL: 'selects'
+; CHECK-THUMB2-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v0 = select i1 undef, i1 undef, i1 undef
 ; CHECK-THUMB2-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
 ; CHECK-THUMB2-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
 ; CHECK-THUMB2-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
@@ -135,12 +139,13 @@
 ; CHECK-THUMB2-RECIP-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
 ; CHECK-MVE-SIZE-LABEL: 'selects'
-; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
-; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
-; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
-; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v4 = select i1 undef, i64 undef, i64 undef
-; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v5 = select i1 undef, float undef, float undef
-; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v6 = select i1 undef, double undef, double undef
+; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v0 = select i1 undef, i1 undef, i1 undef
+; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
+; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
+; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
+; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v4 = select i1 undef, i64 undef, i64 undef
+; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v5 = select i1 undef, float undef, float undef
+; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v6 = select i1 undef, double undef, double undef
 ; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v7 = select <2 x i1> undef, <2 x i8> undef, <2 x i8> undef
 ; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v8 = select <4 x i1> undef, <4 x i8> undef, <4 x i8> undef
 ; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v9 = select <8 x i1> undef, <8 x i8> undef, <8 x i8> undef
@@ -166,12 +171,13 @@
 ; CHECK-MVE-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
 ; CHECK-NEON-SIZE-LABEL: 'selects'
-; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
-; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
-; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
-; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v4 = select i1 undef, i64 undef, i64 undef
-; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v5 = select i1 undef, float undef, float undef
-; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v6 = select i1 undef, double undef, double undef
+; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v0 = select i1 undef, i1 undef, i1 undef
+; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
+; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
+; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
+; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v4 = select i1 undef, i64 undef, i64 undef
+; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v5 = select i1 undef, float undef, float undef
+; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v6 = select i1 undef, double undef, double undef
 ; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v7 = select <2 x i1> undef, <2 x i8> undef, <2 x i8> undef
 ; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v8 = select <4 x i1> undef, <4 x i8> undef, <4 x i8> undef
 ; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v9 = select <8 x i1> undef, <8 x i8> undef, <8 x i8> undef
@@ -197,12 +203,13 @@
 ; CHECK-NEON-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
 ; CHECK-THUMB1-SIZE-LABEL: 'selects'
-; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
-; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
-; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
-; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v4 = select i1 undef, i64 undef, i64 undef
-; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v5 = select i1 undef, float undef, float undef
-; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v6 = select i1 undef, double undef, double undef
+; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v0 = select i1 undef, i1 undef, i1 undef
+; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
+; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
+; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
+; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v4 = select i1 undef, i64 undef, i64 undef
+; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v5 = select i1 undef, float undef, float undef
+; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v6 = select i1 undef, double undef, double undef
 ; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v7 = select <2 x i1> undef, <2 x i8> undef, <2 x i8> undef
 ; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v8 = select <4 x i1> undef, <4 x i8> undef, <4 x i8> undef
 ; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v9 = select <8 x i1> undef, <8 x i8> undef, <8 x i8> undef
@@ -228,12 +235,13 @@
 ; CHECK-THUMB1-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
 ; CHECK-THUMB2-SIZE-LABEL: 'selects'
-; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
-; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
-; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
-; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v4 = select i1 undef, i64 undef, i64 undef
-; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v5 = select i1 undef, float undef, float undef
-; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v6 = select i1 undef, double undef, double undef
+; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v0 = select i1 undef, i1 undef, i1 undef
+; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v1 = select i1 undef, i8 undef, i8 undef
+; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v2 = select i1 undef, i16 undef, i16 undef
+; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v3 = select i1 undef, i32 undef, i32 undef
+; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v4 = select i1 undef, i64 undef, i64 undef
+; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v5 = select i1 undef, float undef, float undef
+; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %v6 = select i1 undef, double undef, double undef
 ; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v7 = select <2 x i1> undef, <2 x i8> undef, <2 x i8> undef
 ; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v8 = select <4 x i1> undef, <4 x i8> undef, <4 x i8> undef
 ; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v9 = select <8 x i1> undef, <8 x i8> undef, <8 x i8> undef
@@ -258,6 +266,7 @@
 ; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v22 = select <5 x i1> undef, <5 x double> undef, <5 x double> undef
 ; CHECK-THUMB2-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
+  %v0 = select i1 undef, i1 undef, i1 undef
   %v1 = select i1 undef, i8 undef, i8 undef
   %v2 = select i1 undef, i16 undef, i16 undef
   %v3 = select i1 undef, i32 undef, i32 undef