diff --git a/infer/src/checkers/ThreadSafety.ml b/infer/src/checkers/ThreadSafety.ml
index 2571b4237..51ba8996e 100644
--- a/infer/src/checkers/ThreadSafety.ml
+++ b/infer/src/checkers/ThreadSafety.ml
@@ -23,6 +23,17 @@ module Summary = Summary.Make (struct
       payload.Specs.threadsafety
   end)
 
+(* we want to consider Builder classes and other safe immutablility-ensuring patterns as
+   thread-safe. we are overly friendly about this for now; any class whose name ends with `Builder`
+   is assumed to be thread-safe. in the future, we can ask for builder classes to be annotated with
+   @Builder and verify that annotated classes satisfy the expected invariants. *)
+let is_builder_class class_name =
+  string_is_suffix "Builder" class_name
+
+let is_call_to_builder_class_method = function
+  | Procname.Java java_pname -> is_builder_class (Procname.java_get_class_name java_pname)
+  | _ -> false
+
 let is_initializer tenv proc_name =
   Procname.is_constructor proc_name ||
   Procname.is_class_initializer proc_name ||
@@ -92,7 +103,9 @@ module TransferFunctions (CFG : ProcCfg.S) = struct
                     let _, read_writestate' =
                       (* TODO (14842325): report on constructors that aren't threadsafe
                          (e.g., constructors that access static fields) *)
-                      if is_unprotected lockstate' && not (is_initializer tenv pn)
+                      if is_unprotected lockstate' &&
+                         not (is_initializer tenv pn) &&
+                         not (is_call_to_builder_class_method pn)
                       then
                         let call_site = CallSite.make pn loc in
                         let callee_readstate =
diff --git a/infer/tests/codetoanalyze/java/threadsafety/Builders.java b/infer/tests/codetoanalyze/java/threadsafety/Builders.java
new file mode 100644
index 000000000..525b74347
--- /dev/null
+++ b/infer/tests/codetoanalyze/java/threadsafety/Builders.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2016 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package codetoanalyze.java.checkers;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableList.Builder;
+
+@ThreadSafe
+public class Builders {
+
+  static class Obj {
+    final String f;
+    String g;
+
+    public Obj(String f, String g) {
+      this.f = f;
+      this.g = g;
+    }
+
+    public static class Builder {
+      String f;
+      String g;
+
+      public Builder setFromObj(Obj input) {
+        this.f = input.f;
+        this.g = input.g;
+        return this;
+      }
+
+      public Obj build() {
+        return new Obj(f, g);
+      }
+
+      public Builder setF(String f) {
+        this.f = f;
+        return this;
+      }
+
+      public Builder setG(String g) {
+        this.g = g;
+        return this;
+      }
+    }
+  }
+
+  public void guavaBuilderOk(ImmutableList.Builder<String> builder) {
+    builder.add("foo");
+    builder.build();
+  }
+
+  public Obj customBuilderOk1(Obj.Builder builder) {
+    builder.setF("f");
+    builder.setG("g");
+    return builder.build();
+  }
+
+  public Obj customBuilderOk2(Obj.Builder builder) {
+    return builder.setF("f").setG("g").build();
+  }
+
+  public Obj customBuilderOk3(Obj input) {
+    Obj.Builder builder = new Obj.Builder();
+    return builder.setFromObj(input).build();
+  }
+
+  public Obj mutateBad(Obj o) {
+    o.g = "";
+    return o;
+  }
+
+  public Obj buildThenMutateBad(Obj input) {
+    Obj.Builder builder = new Obj.Builder();
+    Obj output = builder.setFromObj(input).build();
+    input.g = "";
+    return output;
+  }
+
+}
+
+@ThreadSafe
+class TopLevelBuilder {
+  public String g;
+
+  public void setG(String g) {
+    this.g = g; // still want to warn if the builder is annotated ThreadSafe
+  }
+
+}
diff --git a/infer/tests/codetoanalyze/java/threadsafety/issues.exp b/infer/tests/codetoanalyze/java/threadsafety/issues.exp
index b74e50a74..a86791499 100644
--- a/infer/tests/codetoanalyze/java/threadsafety/issues.exp
+++ b/infer/tests/codetoanalyze/java/threadsafety/issues.exp
@@ -1,3 +1,6 @@
+codetoanalyze/java/threadsafety/Builders.java, Builders$Obj Builders.buildThenMutateBad(Builders$Obj), 3, THREAD_SAFETY_ERROR, [access to codetoanalyze.java.checkers.Builders$Obj.g]
+codetoanalyze/java/threadsafety/Builders.java, Builders$Obj Builders.mutateBad(Builders$Obj), 1, THREAD_SAFETY_ERROR, [access to codetoanalyze.java.checkers.Builders$Obj.g]
+codetoanalyze/java/threadsafety/Builders.java, void TopLevelBuilder.setG(String), 1, THREAD_SAFETY_ERROR, [access to codetoanalyze.java.checkers.TopLevelBuilder.g]
 codetoanalyze/java/threadsafety/Locks.java, void Locks.FP_unlockOneLock(), 4, THREAD_SAFETY_ERROR, [access to codetoanalyze.java.checkers.Locks.f]
 codetoanalyze/java/threadsafety/Locks.java, void Locks.afterReentrantLockUnlockBad(), 3, THREAD_SAFETY_ERROR, [access to codetoanalyze.java.checkers.Locks.f]
 codetoanalyze/java/threadsafety/Locks.java, void Locks.afterUnlockBad(), 3, THREAD_SAFETY_ERROR, [access to codetoanalyze.java.checkers.Locks.f]