diff --git a/lld/COFF/Chunks.cpp b/lld/COFF/Chunks.cpp
--- a/lld/COFF/Chunks.cpp
+++ b/lld/COFF/Chunks.cpp
@@ -661,6 +661,13 @@
             toString(file));
       continue;
     }
+    int addressSizeInBits = file->ctx.config.is64() ? 64 : 32;
+    if (sizeInBits < addressSizeInBits) {
+      warn("runtime pseudo relocation in " + toString(file) + " against " +
+           "symbol " + target->getName() + " is too narrow; only " +
+           Twine(sizeInBits) + " bits wide. This can fail at runtime " +
+           "depending on memory layout.");
+    }
     // sizeInBits is used to initialize the Flags field; currently no
     // other flags are defined.
     res.emplace_back(target, this, rel.VirtualAddress, sizeInBits);
diff --git a/lld/test/CMakeLists.txt b/lld/test/CMakeLists.txt
--- a/lld/test/CMakeLists.txt
+++ b/lld/test/CMakeLists.txt
@@ -51,6 +51,7 @@
     llvm-config
     llvm-cvtres
     llvm-dis
+    llvm-dlltool
     llvm-dwarfdump
     llvm-lib
     llvm-lipo
diff --git a/lld/test/COFF/autoimport-nowarn.s b/lld/test/COFF/autoimport-nowarn.s
new file mode 100644
--- /dev/null
+++ b/lld/test/COFF/autoimport-nowarn.s
@@ -0,0 +1,19 @@
+# REQUIRES: x86
+
+# RUN: echo -e "EXPORTS\nvariable" > %t-lib.def
+# RUN: llvm-dlltool -m i386 -d %t-lib.def -D lib.dll -l %t-lib.lib
+
+# RUN: llvm-mc -triple=i386-windows-gnu %s -filetype=obj -o %t.obj
+# RUN: lld-link -lldmingw -out:%t.exe -entry:main %t.obj %t-lib.lib -verbose 2>&1 | FileCheck --allow-empty %s
+
+# CHECK-NOT: runtime pseudo relocation {{.*}} is too narrow
+
+    .global _main
+    .text
+_main:
+    movl _variable, %eax
+    ret
+
+relocs:
+    .long ___RUNTIME_PSEUDO_RELOC_LIST__
+    .long ___RUNTIME_PSEUDO_RELOC_LIST_END__
diff --git a/lld/test/COFF/autoimport-warn.s b/lld/test/COFF/autoimport-warn.s
new file mode 100644
--- /dev/null
+++ b/lld/test/COFF/autoimport-warn.s
@@ -0,0 +1,29 @@
+# REQUIRES: x86
+
+# RUN: echo -e "EXPORTS\nvariable1 DATA\nvariable2 DATA" > %t-lib.def
+# RUN: llvm-dlltool -m i386:x86-64 -d %t-lib.def -D lib.dll -l %t-lib.lib
+
+# RUN: llvm-mc -triple=x86_64-windows-gnu %s -filetype=obj -o %t.obj
+# RUN: lld-link -lldmingw -out:%t.exe -entry:main %t.obj %t-lib.lib -verbose 2>&1 | FileCheck %s
+
+# CHECK-NOT: runtime pseudo relocation {{.*}} against symbol variable1
+# CHECK: warning: runtime pseudo relocation in {{.*}}.obj against symbol variable2 is too narrow; only 32 bits wide. This can fail at runtime depending on memory layout.
+# CHECK-NOT: runtime pseudo relocation {{.*}} against symbol variable1
+
+    .global main
+    .text
+main:
+    movq .refptr.variable1(%rip), %rax
+    movl (%rax), %eax
+    movl variable2(%rip), %ecx
+    addl %ecx, %eax
+    ret
+
+    .section .rdata$.refptr.variable1,"dr",discard,.refptr.variable1
+    .global .refptr.variable1
+.refptr.variable1:
+    .quad variable1
+
+relocs:
+    .quad __RUNTIME_PSEUDO_RELOC_LIST__
+    .quad __RUNTIME_PSEUDO_RELOC_LIST_END__