Index: llvm/lib/IR/ConstantFold.cpp
===================================================================
--- llvm/lib/IR/ConstantFold.cpp
+++ llvm/lib/IR/ConstantFold.cpp
@@ -1751,9 +1751,15 @@
     case Instruction::FPToSI:
       break; // We can't evaluate floating point casts or truncations.
 
+    case Instruction::BitCast:
+      // If this is a global value cast, check to see if the RHS is also a
+      // GlobalValue.
+      if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0))
+        if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2))
+          return areGlobalsPotentiallyEqual(GV, GV2);
+      LLVM_FALLTHROUGH;
     case Instruction::UIToFP:
     case Instruction::SIToFP:
-    case Instruction::BitCast:
     case Instruction::ZExt:
     case Instruction::SExt:
       // We can't evaluate floating point casts or truncations.
Index: llvm/test/Transforms/InstCombine/2004-11-27-SetCCForCastLargerAndConstant.ll
===================================================================
--- llvm/test/Transforms/InstCombine/2004-11-27-SetCCForCastLargerAndConstant.ll
+++ llvm/test/Transforms/InstCombine/2004-11-27-SetCCForCastLargerAndConstant.ll
@@ -27,11 +27,22 @@
 
 @a = common global i32** null
 @b = common global [1 x i32] zeroinitializer
+@aa = alias i32**, i32*** @a
 
 define i1 @PR28011(i16 %a) {
 ; CHECK-LABEL: @PR28011(
 ; CHECK-NEXT:    [[CONV:%.*]] = sext i16 [[A:%.*]] to i32
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[CONV]], or (i32 zext (i1 icmp ne (i32*** bitcast ([1 x i32]* @b to i32***), i32*** @a) to i32), i32 1)
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[CONV]], or (i32 zext (i1 icmp ne (i32*** bitcast ([1 x i32]* @b to i32***), i32*** @aa) to i32), i32 1)
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %conv = sext i16 %a to i32
+  %cmp = icmp ne i32 %conv, or (i32 zext (i1 icmp ne (i32*** bitcast ([1 x i32]* @b to i32***), i32*** @aa) to i32), i32 1)
+  ret i1 %cmp
+}
+
+define i1 @PR28011a(i16 %a) {
+; CHECK-LABEL: @PR28011a(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i16  [[A:%.*]], 1
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %conv = sext i16 %a to i32
Index: llvm/test/Transforms/InstCombine/icmp-bitcast-func.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstCombine/icmp-bitcast-func.ll
@@ -0,0 +1,20 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+declare i32 @f32(i32**, i32**)
+
+declare i32 @f64(i64**, i64**)
+
+define i1 @icmp_func() {
+; CHECK-LABEL: @icmp_func(
+; CHECK: ret i1 false
+  %cmp = icmp eq i32 (i8*, i8*)* bitcast (i32 (i32**, i32**)* @f32 to i32 (i8*, i8*)*), bitcast (i32 (i64**, i64**)* @f64 to i32 (i8*, i8*)*)
+  ret i1 %cmp
+}
+
+define i1 @icmp_fptr(i32 (i8*, i8*)*) {
+; CHECK-LABEL: @icmp_fptr(
+; CHECK: %cmp = icmp ne i32 (i8*, i8*)* %0, bitcast (i32 (i32**, i32**)* @f32 to i32 (i8*, i8*)*)
+; CHECK: ret i1 %cmp
+  %cmp = icmp ne i32 (i8*, i8*)* bitcast (i32 (i32**, i32**)* @f32 to i32 (i8*, i8*)*), %0
+  ret i1 %cmp
+}
Index: llvm/test/Transforms/InstCombine/pr32686.ll
===================================================================
--- llvm/test/Transforms/InstCombine/pr32686.ll
+++ llvm/test/Transforms/InstCombine/pr32686.ll
@@ -6,11 +6,7 @@
 
 define void @tinkywinky() {
 ; CHECK-LABEL: @tinkywinky(
-; CHECK-NEXT:    [[PATATINO:%.*]] = load i8, i8* @a, align 1
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i8 [[PATATINO]], 0
-; CHECK-NEXT:    [[TMP1:%.*]] = zext i1 [[TOBOOL]] to i32
-; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[TMP1]], or (i32 zext (i1 icmp ne (i32* bitcast (i8* @a to i32*), i32* @b) to i32), i32 2)
-; CHECK-NEXT:    store i32 [[OR1]], i32* @b, align 4
+; CHECK-NEXT:    store i32 3, i32* @b, align 4
 ; CHECK-NEXT:    ret void
 ;
   %patatino = load i8, i8* @a
Index: llvm/test/Transforms/SCCP/ip-ranges-select.ll
===================================================================
--- llvm/test/Transforms/SCCP/ip-ranges-select.ll
+++ llvm/test/Transforms/SCCP/ip-ranges-select.ll
@@ -111,7 +111,7 @@
 
 define i32 @f3_constantexpr_cond(i32 %x, i32 %y) {
 ; CHECK-LABEL: define i32 @f3_constantexpr_cond(i32 %x, i32 %y)
-; CHECK-NEXT:   %sel.1 = select i1 icmp eq (i32* bitcast (i32 (i32, i32)* @f3_constantexpr_cond to i32*), i32* @GV), i32 %x, i32 %y
+; CHECK-NEXT:   %sel.1 = select i1 false, i32 %x, i32 %y
 ; CHECK-NEXT:   ret i32 %sel.1
 ;
   %sel.1 = select i1 icmp eq (i32* bitcast (i32 (i32, i32)* @f3_constantexpr_cond to i32*), i32* @GV), i32 %x, i32 %y
Index: llvm/test/Transforms/SCCP/undef-resolve.ll
===================================================================
--- llvm/test/Transforms/SCCP/undef-resolve.ll
+++ llvm/test/Transforms/SCCP/undef-resolve.ll
@@ -259,7 +259,7 @@
 define i32 @test11(i1 %tobool) {
 ; CHECK-LABEL: @test11(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[SHR4:%.*]] = ashr i32 undef, zext (i1 icmp eq (i32* bitcast (i32 (i1)* @test11 to i32*), i32* @GV) to i32)
+; CHECK-NEXT:    [[SHR4:%.*]] = ashr i32 undef, 0
 ; CHECK-NEXT:    ret i32 [[SHR4]]
 ;
 entry:
Index: llvm/test/Transforms/SimplifyCFG/PR17073.ll
===================================================================
--- llvm/test/Transforms/SimplifyCFG/PR17073.ll
+++ llvm/test/Transforms/SimplifyCFG/PR17073.ll
@@ -11,8 +11,9 @@
 target datalayout = "e-m:o-p:32:32-f64:32:64-f80:128-n8:16:32-S128"
 target triple = "i386-apple-macosx10.9.0"
 
-@a = common global i32 0, align 4
+@g = common global i32 0, align 4
 @b = common global i8 0, align 1
+@a = alias i32, i32* @g
 
 define i32* @can_trap1() {
 ; CHECK-LABEL: @can_trap1(
@@ -98,3 +99,75 @@
   %storemerge = phi i32* [ null, %entry ],[ null, %block2 ], [ select (i1 icmp eq (i64 add (i64 2, i64 zext (i1 icmp eq (i32* bitcast (i8* @b to i32*), i32* @a) to i64)), i64 0), i32* null, i32* @a), %block1 ]
   ret i32* %storemerge
 }
+
+; The following are the original test cases using global @g, and can be simplified now.
+
+define i32* @no_trap1() {
+; CHECK-LABEL: @no_trap1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* @g, align 4
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[TMP0]], 0
+; CHECK-NEXT:    ret i32* null
+;
+entry:
+  %0 = load i32, i32* @g, align 4
+  %tobool = icmp eq i32 %0, 0
+  br i1 %tobool, label %exit, label %block1
+
+block1:
+  br i1 icmp eq (i32* bitcast (i8* @b to i32*), i32* @g), label %exit, label %block2
+
+block2:
+  br label %exit
+
+exit:
+  %storemerge = phi i32* [ null, %entry ],[ null, %block2 ], [ select (i1 icmp eq (i64 urem (i64 2, i64 zext (i1 icmp eq (i32* bitcast (i8* @b to i32*), i32* @g) to i64)), i64 0), i32* null, i32* @g), %block1 ]
+  ret i32* %storemerge
+}
+
+define i32* @no_trap2() {
+; CHECK-LABEL: @no_trap2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* @g, align 4
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[TMP0]], 0
+; CHECK-NEXT:    [[STOREMERGE:%.*]] = select i1 [[TOBOOL]], i32* @g, i32* null
+; CHECK-NEXT:    ret i32* [[STOREMERGE]]
+;
+entry:
+  %0 = load i32, i32* @g, align 4
+  %tobool = icmp eq i32 %0, 0
+  br i1 %tobool, label %exit, label %block1
+
+block1:
+  br i1 icmp eq (i32* bitcast (i8* @b to i32*), i32* @g), label %exit, label %block2
+
+block2:
+  br label %exit
+
+exit:
+  %storemerge = phi i32* [ select (i1 icmp eq (i64 urem (i64 2, i64 zext (i1 icmp eq (i32* bitcast (i8* @b to i32*), i32* @g) to i64)), i64 0), i32* null, i32* @g), %entry ],[ null, %block2 ], [ null, %block1 ]
+  ret i32* %storemerge
+}
+
+define i32* @no_trap3() {
+; CHECK-LABEL: @no_trap3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* @g, align 4
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[TMP0]], 0
+; CHECK-NEXT:    ret i32* null
+;
+entry:
+  %0 = load i32, i32* @g, align 4
+  %tobool = icmp eq i32 %0, 0
+  br i1 %tobool, label %exit, label %block1
+
+block1:
+  br i1 icmp eq (i32* bitcast (i8* @b to i32*), i32* @g), label %exit, label %block2
+
+block2:
+  br label %exit
+
+exit:
+  %storemerge = phi i32* [ null, %entry ],[ null, %block2 ], [ select (i1 icmp eq (i64 add (i64 2, i64 zext (i1 icmp eq (i32* bitcast (i8* @b to i32*), i32* @g) to i64)), i64 0), i32* null, i32* @g), %block1 ]
+  ret i32* %storemerge
+}