Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4610,10 +4610,16 @@
   // TODO: Some instructions are guaranteed to return neither undef
   // nor poison if their arguments are not poison/undef.
 
-  // TODO: Deal with other Constant subclasses.
-  if (isa<ConstantInt>(V) || isa<GlobalVariable>(V))
+  if (isa<GlobalVariable>(V))
     return true;
 
+  // Constants (except possibly for constant expressions) are never poison,
+  // so check for ConstantExpr or undef.
+  if (auto *C = dyn_cast<Constant>(V)) {
+    return !isa<UndefValue>(C) && !isa<ConstantExpr>(C) &&
+           !C->containsUndefElement() && !C->containsConstantExpression();
+  }
+
   if (auto PN = dyn_cast<PHINode>(V)) {
     if (llvm::all_of(PN->incoming_values(), [](const Use &U) {
           return isa<ConstantInt>(U.get());
Index: llvm/test/Transforms/InstSimplify/freeze.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/freeze.ll
+++ llvm/test/Transforms/InstSimplify/freeze.ll
@@ -21,8 +21,7 @@
 
 define float @make_const2() {
 ; CHECK-LABEL: @make_const2(
-; CHECK-NEXT:    [[X:%.*]] = freeze float 1.000000e+01
-; CHECK-NEXT:    ret float [[X]]
+; CHECK-NEXT:    ret float 1.000000e+01
 ;
   %x = freeze float 10.0
   ret float %x
@@ -40,8 +39,7 @@
 
 define i32()* @make_const_fn() {
 ; CHECK-LABEL: @make_const_fn(
-; CHECK-NEXT:    [[K:%.*]] = freeze i32 ()* @make_const
-; CHECK-NEXT:    ret i32 ()* [[K]]
+; CHECK-NEXT:    ret i32 ()* @make_const
 ;
   %k = freeze i32()* @make_const
   ret i32()* %k
@@ -49,8 +47,7 @@
 
 define i32* @make_const_null() {
 ; CHECK-LABEL: @make_const_null(
-; CHECK-NEXT:    [[K:%.*]] = freeze i32* null
-; CHECK-NEXT:    ret i32* [[K]]
+; CHECK-NEXT:    ret i32* null
 ;
   %k = freeze i32* null
   ret i32* %k
@@ -58,8 +55,7 @@
 
 define <2 x i32> @constvector() {
 ; CHECK-LABEL: @constvector(
-; CHECK-NEXT:    [[X:%.*]] = freeze <2 x i32> <i32 0, i32 1>
-; CHECK-NEXT:    ret <2 x i32> [[X]]
+; CHECK-NEXT:    ret <2 x i32> <i32 0, i32 1>
 ;
   %x = freeze <2 x i32> <i32 0, i32 1>
   ret <2 x i32> %x
@@ -67,8 +63,7 @@
 
 define <3 x i5> @constvector_weird() {
 ; CHECK-LABEL: @constvector_weird(
-; CHECK-NEXT:    [[X:%.*]] = freeze <3 x i5> <i5 0, i5 1, i5 10>
-; CHECK-NEXT:    ret <3 x i5> [[X]]
+; CHECK-NEXT:    ret <3 x i5> <i5 0, i5 1, i5 10>
 ;
   %x = freeze <3 x i5> <i5 0, i5 1, i5 42>
   ret <3 x i5> %x
@@ -76,13 +71,14 @@
 
 define <2 x float> @constvector_FP() {
 ; CHECK-LABEL: @constvector_FP(
-; CHECK-NEXT:    [[X:%.*]] = freeze <2 x float> <float 0.000000e+00, float 1.000000e+00>
-; CHECK-NEXT:    ret <2 x float> [[X]]
+; CHECK-NEXT:    ret <2 x float> <float 0.000000e+00, float 1.000000e+00>
 ;
   %x = freeze <2 x float> <float 0.0, float 1.0>
   ret <2 x float> %x
 }
 
+; Negative test
+
 define <2 x i32> @constvector_noopt() {
 ; CHECK-LABEL: @constvector_noopt(
 ; CHECK-NEXT:    [[X:%.*]] = freeze <2 x i32> <i32 0, i32 undef>
@@ -92,6 +88,8 @@
   ret <2 x i32> %x
 }
 
+; Negative test
+
 define <3 x i5> @constvector_weird_noopt() {
 ; CHECK-LABEL: @constvector_weird_noopt(
 ; CHECK-NEXT:    [[X:%.*]] = freeze <3 x i5> <i5 0, i5 undef, i5 10>
@@ -101,6 +99,8 @@
   ret <3 x i5> %x
 }
 
+; Negative test
+
 define <2 x float> @constvector_FP_noopt() {
 ; CHECK-LABEL: @constvector_FP_noopt(
 ; CHECK-NEXT:    [[X:%.*]] = freeze <2 x float> <float 0.000000e+00, float undef>
@@ -112,6 +112,8 @@
 
 @g = external global i16, align 1
 
+; Negative test
+
 define float @constant_expr() {
 ; CHECK-LABEL: @constant_expr(
 ; CHECK-NEXT:    [[R:%.*]] = freeze float bitcast (i32 ptrtoint (i16* @g to i32) to float)
@@ -121,6 +123,8 @@
   ret float %r
 }
 
+; Negative test
+
 define <2 x i31> @vector_element_constant_expr() {
 ; CHECK-LABEL: @vector_element_constant_expr(
 ; CHECK-NEXT:    [[R:%.*]] = freeze <2 x i31> <i31 34, i31 ptrtoint (i16* @g to i31)>
@@ -195,8 +199,7 @@
 
 define i32* @gep_inbounds_null() {
 ; CHECK-LABEL: @gep_inbounds_null(
-; CHECK-NEXT:    [[K:%.*]] = freeze i32* null
-; CHECK-NEXT:    ret i32* [[K]]
+; CHECK-NEXT:    ret i32* null
 ;
   %p = getelementptr inbounds i32, i32* null, i32 0
   %k = freeze i32* %p