diff --git a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -1316,6 +1316,24 @@
     if (Instruction *Result = foldPHIArgOpIntoPHI(PN))
       return Result;
 
+  // If the incoming values are pointer casts of the same original value,
+  // replace the phi with a single cast.
+  if (PN.getType()->isPointerTy()) {
+    Value *IV0 = PN.getIncomingValue(0);
+    Value *IV0Stripped = IV0->stripPointerCasts();
+    // Set to keep track of values known to be equal to IV0Stripped after
+    // stripping pointer casts.
+    SmallPtrSet<Value *, 4> CheckedIVs;
+    CheckedIVs.insert(IV0);
+    if (IV0 != IV0Stripped &&
+        all_of(PN.incoming_values(), [&CheckedIVs, IV0Stripped](Value *IV) {
+          return !CheckedIVs.insert(IV).second ||
+                 IV0Stripped == IV->stripPointerCasts();
+        })) {
+      return CastInst::CreatePointerCast(IV0Stripped, PN.getType());
+    }
+  }
+
   // If this is a trivial cycle in the PHI node graph, remove it.  Basically, if
   // this PHI only has a single use (a PHI), and if that PHI only has one use (a
   // PHI)... break the cycle.
diff --git a/llvm/test/Transforms/InstCombine/phi-pointercasts.ll b/llvm/test/Transforms/InstCombine/phi-pointercasts.ll
--- a/llvm/test/Transforms/InstCombine/phi-pointercasts.ll
+++ b/llvm/test/Transforms/InstCombine/phi-pointercasts.ll
@@ -4,16 +4,15 @@
 define void @test_bitcast_1(i1 %c, i32* %ptr) {
 ; CHECK-LABEL: @test_bitcast_1(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[CAST_0:%.*]] = bitcast i32* [[PTR:%.*]] to i8*
 ; CHECK-NEXT:    br i1 [[C:%.*]], label [[B0:%.*]], label [[B1:%.*]]
 ; CHECK:       b0:
+; CHECK-NEXT:    [[CAST_0:%.*]] = bitcast i32* [[PTR:%.*]] to i8*
 ; CHECK-NEXT:    call void @use(i8* [[CAST_0]])
 ; CHECK-NEXT:    br label [[END:%.*]]
 ; CHECK:       b1:
-; CHECK-NEXT:    [[CAST_1:%.*]] = bitcast i32* [[PTR]] to i8*
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[P:%.*]] = phi i8* [ [[CAST_0]], [[B0]] ], [ [[CAST_1]], [[B1]] ]
+; CHECK-NEXT:    [[P:%.*]] = bitcast i32* [[PTR]] to i8*
 ; CHECK-NEXT:    store i8 0, i8* [[P]], align 1
 ; CHECK-NEXT:    ret void
 ;
@@ -40,14 +39,13 @@
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br i1 [[C:%.*]], label [[B0:%.*]], label [[B1:%.*]]
 ; CHECK:       b0:
-; CHECK-NEXT:    [[CAST_0:%.*]] = bitcast i32* [[PTR:%.*]] to i8*
 ; CHECK-NEXT:    br label [[END:%.*]]
 ; CHECK:       b1:
-; CHECK-NEXT:    [[CAST_1:%.*]] = bitcast i32* [[PTR]] to i8*
+; CHECK-NEXT:    [[CAST_1:%.*]] = bitcast i32* [[PTR:%.*]] to i8*
 ; CHECK-NEXT:    call void @use(i8* [[CAST_1]])
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[P:%.*]] = phi i8* [ [[CAST_0]], [[B0]] ], [ [[CAST_1]], [[B1]] ]
+; CHECK-NEXT:    [[P:%.*]] = bitcast i32* [[PTR]] to i8*
 ; CHECK-NEXT:    store i8 0, i8* [[P]], align 1
 ; CHECK-NEXT:    ret void
 ;
@@ -76,14 +74,13 @@
 ; CHECK-NEXT:    [[LOAD_PTR:%.*]] = load i32*, i32** [[PTR:%.*]], align 8
 ; CHECK-NEXT:    br i1 [[C:%.*]], label [[B0:%.*]], label [[B1:%.*]]
 ; CHECK:       b0:
-; CHECK-NEXT:    [[CAST_0:%.*]] = bitcast i32* [[LOAD_PTR]] to i8*
 ; CHECK-NEXT:    br label [[END:%.*]]
 ; CHECK:       b1:
 ; CHECK-NEXT:    [[CAST_1:%.*]] = bitcast i32* [[LOAD_PTR]] to i8*
 ; CHECK-NEXT:    call void @use(i8* [[CAST_1]])
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[P:%.*]] = phi i8* [ [[CAST_0]], [[B0]] ], [ [[CAST_1]], [[B1]] ]
+; CHECK-NEXT:    [[P:%.*]] = bitcast i32* [[LOAD_PTR]] to i8*
 ; CHECK-NEXT:    store i8 0, i8* [[P]], align 1
 ; CHECK-NEXT:    ret void
 ;
@@ -218,10 +215,9 @@
 ; CHECK-NEXT:    call void @use(i8* [[CAST_0]])
 ; CHECK-NEXT:    br label [[END:%.*]]
 ; CHECK:       b1:
-; CHECK-NEXT:    [[CAST_1:%.*]] = bitcast i32* [[PTR]] to i8*
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[P:%.*]] = phi i8* [ [[CAST_0]], [[B0]] ], [ [[CAST_1]], [[B1]] ]
+; CHECK-NEXT:    [[P:%.*]] = bitcast i32* [[PTR]] to i8*
 ; CHECK-NEXT:    store i8 0, i8* [[P]], align 1
 ; CHECK-NEXT:    ret void
 ;
@@ -287,10 +283,9 @@
 ; CHECK-NEXT:    br label [[END:%.*]]
 ; CHECK:       b1:
 ; CHECK-NEXT:    call void @use.i32(i32* [[PTR]])
-; CHECK-NEXT:    [[CAST_3:%.*]] = bitcast i32* [[PTR]] to i8*
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[P:%.*]] = phi i8* [ [[CAST_0]], [[B0]] ], [ [[CAST_3]], [[B1]] ]
+; CHECK-NEXT:    [[P:%.*]] = bitcast i32* [[PTR]] to i8*
 ; CHECK-NEXT:    store i8 0, i8* [[P]], align 1
 ; CHECK-NEXT:    ret void
 ;
@@ -509,18 +504,17 @@
 define void @test_addrspacecast_1(i1 %c, i32* %ptr) {
 ; CHECK-LABEL: @test_addrspacecast_1(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[TMP0:%.*]] = bitcast i32* [[PTR:%.*]] to i8*
-; CHECK-NEXT:    [[CAST_1:%.*]] = addrspacecast i8* [[TMP0]] to i8 addrspace(1)*
 ; CHECK-NEXT:    br i1 [[C:%.*]], label [[B0:%.*]], label [[B1:%.*]]
 ; CHECK:       b0:
-; CHECK-NEXT:    [[TMP1:%.*]] = bitcast i32* [[PTR]] to i8*
-; CHECK-NEXT:    [[CAST_0:%.*]] = addrspacecast i8* [[TMP1]] to i8 addrspace(1)*
 ; CHECK-NEXT:    br label [[END:%.*]]
 ; CHECK:       b1:
+; CHECK-NEXT:    [[TMP0:%.*]] = bitcast i32* [[PTR:%.*]] to i8*
+; CHECK-NEXT:    [[CAST_1:%.*]] = addrspacecast i8* [[TMP0]] to i8 addrspace(1)*
 ; CHECK-NEXT:    call void @use.i8.addrspace1(i8 addrspace(1)* [[CAST_1]])
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[P:%.*]] = phi i8 addrspace(1)* [ [[CAST_0]], [[B0]] ], [ [[CAST_1]], [[B1]] ]
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast i32* [[PTR]] to i8*
+; CHECK-NEXT:    [[P:%.*]] = addrspacecast i8* [[TMP1]] to i8 addrspace(1)*
 ; CHECK-NEXT:    store i8 0, i8 addrspace(1)* [[P]], align 1
 ; CHECK-NEXT:    ret void
 ;