diff --git a/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h b/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
--- a/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
@@ -756,6 +756,7 @@
   bool matchBuildVectorIdentityFold(MachineInstr &MI, Register &MatchInfo);
   bool matchTruncBuildVectorFold(MachineInstr &MI, Register &MatchInfo);
   bool matchTruncLshrBuildVectorFold(MachineInstr &MI, Register &MatchInfo);
+  bool matchBitcastBitcastFold(MachineInstr &MI, Register &MatchInfo);
 
   /// Transform:
   ///   (x + y) - y -> x
diff --git a/llvm/include/llvm/Target/GlobalISel/Combine.td b/llvm/include/llvm/Target/GlobalISel/Combine.td
--- a/llvm/include/llvm/Target/GlobalISel/Combine.td
+++ b/llvm/include/llvm/Target/GlobalISel/Combine.td
@@ -967,6 +967,12 @@
          [{ return Helper.matchSubAddSameReg(*${root}, ${matchinfo}); }]),
   (apply [{ Helper.applyBuildFn(*${root}, ${matchinfo}); }])>;
 
+def bitcast_bitcast_fold : GICombineRule<
+  (defs root:$op, register_matchinfo:$matchinfo),
+  (match (wip_match_opcode G_BITCAST):$op,
+      [{ return Helper.matchBitcastBitcastFold(*${op}, ${matchinfo}); }]),
+  (apply [{ Helper.replaceSingleDefInstWithReg(*${op}, ${matchinfo}); }])>;
+
 def select_to_minmax: GICombineRule<
   (defs root:$root, build_fn_matchinfo:$info),
   (match (wip_match_opcode G_SELECT):$root,
@@ -993,7 +999,8 @@
                                         fneg_fneg_fold, right_identity_one,
                                         add_sub_reg, buildvector_identity_fold,
                                         trunc_buildvector_fold,
-                                        trunc_lshr_buildvector_fold]>;
+                                        trunc_lshr_buildvector_fold,
+                                        bitcast_bitcast_fold]>;
 
 def const_combines : GICombineGroup<[constant_fp_op, const_ptradd_to_i2p,
                                      overlapping_and, mulo_by_2, mulo_by_0,
diff --git a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
--- a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -5929,6 +5929,21 @@
          MatchTy == MRI.getType(MI.getOperand(0).getReg());
 }
 
+bool CombinerHelper::matchBitcastBitcastFold(MachineInstr &MI,
+                                             Register &MatchInfo) {
+  // Matches two bitcasts in a row that cancel each-other.
+
+  Register Src = MI.getOperand(1).getReg();
+  MachineInstr *SrcMI = getDefIgnoringCopies(Src, MRI);
+
+  if (SrcMI->getOpcode() != TargetOpcode::G_BITCAST)
+    return false;
+
+  Register Dst = MI.getOperand(0).getReg();
+  MatchInfo = SrcMI->getOperand(1).getReg();
+  return MRI.getType(MatchInfo) == MRI.getType(Dst);
+}
+
 unsigned CombinerHelper::getFPMinMaxOpcForSelect(
     CmpInst::Predicate Pred, LLT DstTy,
     SelectPatternNaNBehaviour VsNaNRetVal) const {
diff --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/prelegalizer-combiner-redundant-bitcast.mir b/llvm/test/CodeGen/AMDGPU/GlobalISel/prelegalizer-combiner-redundant-bitcast.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/prelegalizer-combiner-redundant-bitcast.mir
@@ -0,0 +1,55 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -run-pass=amdgpu-prelegalizer-combiner -verify-machineinstrs -o - %s | FileCheck %s
+
+---
+name: s32_bitcast
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $vgpr0
+    ; CHECK-LABEL: name: s32_bitcast
+    ; CHECK: liveins: $vgpr0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %src:_(<2 x s16>) = COPY $vgpr0
+    ; CHECK-NEXT: $vgpr0 = COPY %src(<2 x s16>)
+    %src:_(<2 x s16>) = COPY $vgpr0
+    %b1:_(s32) = G_BITCAST %src
+    %b2:_(<2 x s16>) = G_BITCAST %b1
+    $vgpr0 = COPY %b2
+...
+
+---
+name: s64_bitcast
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+    ; CHECK-LABEL: name: s64_bitcast
+    ; CHECK: liveins: $vgpr0_vgpr1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %src:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    ; CHECK-NEXT: $vgpr0_vgpr1 = COPY %src(<2 x s32>)
+    %src:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    %b1:_(s64) = G_BITCAST %src
+    %b2:_(<2 x s32>) = G_BITCAST %b1
+    $vgpr0_vgpr1 = COPY %b2
+...
+
+---
+name: s64_bitcast_differentypes_nofold
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+    ; CHECK-LABEL: name: s64_bitcast_differentypes_nofold
+    ; CHECK: liveins: $vgpr0_vgpr1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %src:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    ; CHECK-NEXT: %b1:_(s64) = G_BITCAST %src(<2 x s32>)
+    ; CHECK-NEXT: %b2:_(<4 x s16>) = G_BITCAST %b1(s64)
+    ; CHECK-NEXT: $vgpr0_vgpr1 = COPY %b2(<4 x s16>)
+    %src:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    %b1:_(s64) = G_BITCAST %src
+    %b2:_(<4 x s16>) = G_BITCAST %b1
+    $vgpr0_vgpr1 = COPY %b2
+...