Index: lib/Transforms/InstCombine/InstCombineSelect.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -58,17 +58,22 @@
 /// constant of a binop.
 static Instruction *foldSelectBinOpIdentity(SelectInst &Sel) {
   // The select condition must be an equality compare with a constant operand.
-  // TODO: Support FP compares.
   Value *X;
   Constant *C;
   CmpInst::Predicate Pred;
-  if (!match(Sel.getCondition(), m_ICmp(Pred, m_Value(X), m_Constant(C))) ||
-      !ICmpInst::isEquality(Pred))
+  if (!match(Sel.getCondition(), m_Cmp(Pred, m_Value(X), m_Constant(C))))
+    return nullptr;
+
+  bool IsEq;
+  if (ICmpInst::isEquality(Pred))
+    IsEq = Pred == ICmpInst::ICMP_EQ;
+  else if (FCmpInst::isEquality(Pred))
+    IsEq = Pred == FCmpInst::FCMP_OEQ || Pred == FCmpInst::FCMP_UEQ;
+  else
     return nullptr;
 
   // A select operand must be a binop, and the compare constant must be the
   // identity constant for that binop.
-  bool IsEq = Pred == ICmpInst::ICMP_EQ;
   BinaryOperator *BO;
   if (!match(Sel.getOperand(IsEq ? 1 : 2), m_BinOp(BO)) ||
       ConstantExpr::getBinOpIdentity(BO->getOpcode(), BO->getType(), true) != C)
Index: test/Transforms/InstCombine/select-binop-cmp.ll
===================================================================
--- test/Transforms/InstCombine/select-binop-cmp.ll
+++ test/Transforms/InstCombine/select-binop-cmp.ll
@@ -143,8 +143,7 @@
 define float @select_fadd_fcmp(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fadd_fcmp(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fadd float [[X]], [[Z:%.*]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, -0.0
@@ -156,8 +155,7 @@
 define float @select_fadd_fcmp_2(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fadd_fcmp_2(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp ueq float [[X:%.*]], -0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fadd float [[X]], [[Z:%.*]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp ueq float %x, -0.0
@@ -169,8 +167,7 @@
 define float @select_fadd_fcmp_3(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fadd_fcmp_3(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp one float [[X:%.*]], -0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fadd float [[Z:%.*]], [[X]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[Z:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp one float %x, -0.0
@@ -182,8 +179,7 @@
 define float @select_fadd_fcmp_4(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fadd_fcmp_4(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp une float [[X:%.*]], -0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fadd float [[Z:%.*]], [[X]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[Z:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp une float %x, -0.0
@@ -195,8 +191,7 @@
 define float @select_fmul_fcmp(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fmul_fcmp(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fmul float [[X]], [[Z:%.*]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, 1.0
@@ -208,8 +203,7 @@
 define float @select_fsub_fcmp(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fsub_fcmp(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fsub float [[Z:%.*]], [[X]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, 0.0
@@ -221,8 +215,7 @@
 define float @select_fdiv_fcmp(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fdiv_fcmp(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fdiv float [[Z:%.*]], [[X]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, 1.0
@@ -349,6 +342,62 @@
   ret i32 %C
 }
 
+define float @select_fadd_fcmp_nan_1(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fadd_fcmp_nan_1(
+; CHECK-NEXT:    [[A:%.*]] = fcmp nnan oeq float [[X:%.*]], -0.000000e+00
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = fcmp nnan oeq float %x, -0.0
+  %B = fadd float %x, %z
+  %C = select i1 %A, float %B, float %y
+  ret float %C
+}
+
+define float @select_fadd_fcmp_nan_2(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fadd_fcmp_nan_2(
+; CHECK-NEXT:    ret float [[Y:%.*]]
+;
+  %A = fcmp oeq float %x, 0x7FF8000000000000
+  %B = fadd float %x, %z
+  %C = select i1 %A, float %B, float %y
+  ret float %C
+}
+
+define float @select_fadd_fcmp_nan_3(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fadd_fcmp_nan_3(
+; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float 0x7FF8000000000000, float [[Y:%.*]]
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = fcmp oeq float %x, -0.0
+  %B = fadd float %x, 0x7FF8000000000000
+  %C = select i1 %A, float %B, float %y
+  ret float %C
+}
+
+define float @select_fadd_fcmp_nan_4(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fadd_fcmp_nan_4(
+; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float 0x7FF8000000000000
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = fcmp oeq float %x, -0.0
+  %B = fadd float %x, %z
+  %C = select i1 %A, float %B, float 0x7FF8000000000000
+  ret float %C
+}
+
+define float @select_fadd_fcmp_nan_5(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fadd_fcmp_nan_5(
+; CHECK-NEXT:    ret float [[Y:%.*]]
+;
+  %A = fcmp oeq float 0x7FF8000000000000, -0.0
+  %B = fadd float 0x7FF8000000000000, %z
+  %C = select i1 %A, float %B, float %y
+  ret float %C
+}
+
 ; Negative tests
 define i32 @select_xor_icmp_bad_1(i32 %x, i32 %y, i32 %z, i32 %k) {
 ; CHECK-LABEL: @select_xor_icmp_bad_1(