Index: lld/COFF/Chunks.h
===================================================================
--- lld/COFF/Chunks.h
+++ lld/COFF/Chunks.h
@@ -217,6 +217,11 @@
 
   ArrayRef<coff_relocation> Relocs;
 
+  // The associative .pdata section if this is a COMDAT chunk.
+  // A section and its associative .pdata must be ICFed as a unit.
+  // This field makes it convenient to access the .pdata during ICF.
+  SectionChunk *Pdata = nullptr;
+
 private:
   StringRef SectionName;
   std::vector<SectionChunk *> AssocChildren;
Index: lld/COFF/Chunks.cpp
===================================================================
--- lld/COFF/Chunks.cpp
+++ lld/COFF/Chunks.cpp
@@ -363,6 +363,8 @@
 
 void SectionChunk::addAssociative(SectionChunk *Child) {
   AssocChildren.push_back(Child);
+  if (Child->getSectionName().split('$').first == ".pdata")
+    Pdata = Child;
 }
 
 static uint8_t getBaserelType(const coff_relocation &Rel) {
@@ -440,6 +442,10 @@
 void SectionChunk::replace(SectionChunk *Other) {
   Other->Repl = Repl;
   Other->Live = false;
+  if (Pdata) {
+    Other->Pdata->Repl = Pdata->Repl;
+    Other->Pdata->Live = false;
+  }
 }
 
 CommonChunk::CommonChunk(const COFFSymbolRef S) : Sym(S) {
Index: lld/COFF/ICF.cpp
===================================================================
--- lld/COFF/ICF.cpp
+++ lld/COFF/ICF.cpp
@@ -149,7 +149,9 @@
   return A->getOutputCharacteristics() == B->getOutputCharacteristics() &&
          A->SectionName == B->SectionName && A->Alignment == B->Alignment &&
          A->Header->SizeOfRawData == B->Header->SizeOfRawData &&
-         A->Checksum == B->Checksum && A->getContents() == B->getContents();
+         A->Checksum == B->Checksum && A->getContents() == B->getContents() &&
+         (A->Pdata ? (B->Pdata && equalsConstant(A->Pdata, B->Pdata))
+                   : !B->Pdata);
 }
 
 // Compare "moving" part of two sections, namely relocation targets.
@@ -165,7 +167,10 @@
         return D1->getChunk()->Class[Cnt % 2] == D2->getChunk()->Class[Cnt % 2];
     return false;
   };
-  return std::equal(A->Relocs.begin(), A->Relocs.end(), B->Relocs.begin(), Eq);
+  return std::equal(A->Relocs.begin(), A->Relocs.end(), B->Relocs.begin(),
+                    Eq) &&
+         (A->Pdata ? (B->Pdata && equalsVariable(A->Pdata, B->Pdata))
+                   : !B->Pdata);
 }
 
 // Find the first Chunk after Begin that has a different class from Begin.
Index: lld/test/COFF/icf-pdata.s
===================================================================
--- /dev/null
+++ lld/test/COFF/icf-pdata.s
@@ -0,0 +1,92 @@
+# RUN: llvm-mc %s -triple x86_64-windows-msvc -filetype=obj -o %t.obj
+# RUN: lld-link %t.obj -dll -noentry -out:%t.dll -merge:.xdata=.xdata
+# RUN: llvm-readobj -sections -coff-exports %t.dll | FileCheck %s
+
+# CHECK:         Name: .pdata
+# CHECK-NEXT:    VirtualSize: 0x18
+# CHECK:         Name: .xdata
+# CHECK-NEXT:    VirtualSize: 0x10
+
+# CHECK:         Name: xdata1
+# CHECK-NEXT:    RVA: 0x1010
+# CHECK:         Name: xdata1a
+# CHECK-NEXT:    RVA: 0x1010
+# CHECK:         Name: xdata1b
+# CHECK-NEXT:    RVA: 0x1030
+
+	.text
+callee:
+	ret
+
+	.def	 xdata1;
+	.scl	2;
+	.type	32;
+	.endef
+	.section	.text,"xr",one_only,xdata1
+	.globl	xdata1                  # -- Begin function xdata1
+	.p2align	4, 0x90
+xdata1:                                 # @xdata1
+.seh_proc xdata1
+# BB#0:                                 # %entry
+	subq	$40, %rsp
+	.seh_stackalloc 40
+	.seh_endprologue
+	callq	callee
+	nop
+	addq	$40, %rsp
+	jmp	callee                  # TAILCALL
+	.seh_handlerdata
+	.section	.text,"xr",one_only,xdata1
+	.seh_endproc
+                                        # -- End function
+
+# xdata1a is identical to xdata1, so it should be ICFd, and so should its pdata.
+	.def	 xdata1a;
+	.scl	2;
+	.type	32;
+	.endef
+	.section	.text,"xr",one_only,xdata1a
+	.globl	xdata1a                  # -- Begin function xdata1a
+	.p2align	4, 0x90
+xdata1a:                                 # @xdata1a
+.seh_proc xdata1a
+# BB#0:                                 # %entry
+	subq	$40, %rsp
+	.seh_stackalloc 40
+	.seh_endprologue
+	callq	callee
+	nop
+	addq	$40, %rsp
+	jmp	callee                  # TAILCALL
+	.seh_handlerdata
+	.section	.text,"xr",one_only,xdata1a
+	.seh_endproc
+
+# xdata1b's text is identical to xdata1, but its xdata specifies a different
+# stack size, so it cannot be ICFd with xdata1.
+	.def	 xdata1b;
+	.scl	2;
+	.type	32;
+	.endef
+	.section	.text,"xr",one_only,xdata1b
+	.globl	xdata1b                  # -- Begin function xdata1b
+	.p2align	4, 0x90
+xdata1b:                                 # @xdata1b
+.seh_proc xdata1b
+# BB#0:                                 # %entry
+	subq	$40, %rsp
+	.seh_stackalloc 48
+	.seh_endprologue
+	callq	callee
+	nop
+	addq	$40, %rsp
+	jmp	callee                  # TAILCALL
+	.seh_handlerdata
+	.section	.text,"xr",one_only,xdata1b
+	.seh_endproc
+                                        # -- End function
+
+	.section	.drectve,"yn"
+	.ascii	" -export:xdata1"
+	.ascii	" -export:xdata1a"
+	.ascii	" -export:xdata1b"