diff --git a/lldb/include/lldb/Target/Target.h b/lldb/include/lldb/Target/Target.h
--- a/lldb/include/lldb/Target/Target.h
+++ b/lldb/include/lldb/Target/Target.h
@@ -225,9 +225,12 @@
   void DisableASLRValueChangedCallback();
   void DisableSTDIOValueChangedCallback();
 
+  Environment ComputeEnvironment() const;
+
   // Member variables.
   ProcessLaunchInfo m_launch_info;
   std::unique_ptr<TargetExperimentalProperties> m_experimental_properties_up;
+  Target *m_target;
 };
 
 class EvaluateExpressionOptions {
diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -3357,16 +3357,13 @@
 
 class TargetOptionValueProperties : public OptionValueProperties {
 public:
-  TargetOptionValueProperties(ConstString name)
-      : OptionValueProperties(name), m_target(nullptr), m_got_host_env(false) {}
+  TargetOptionValueProperties(ConstString name) : OptionValueProperties(name) {}
 
   // This constructor is used when creating TargetOptionValueProperties when it
   // is part of a new lldb_private::Target instance. It will copy all current
   // global property values as needed
-  TargetOptionValueProperties(Target *target,
-                              const TargetPropertiesSP &target_properties_sp)
-      : OptionValueProperties(*target_properties_sp->GetValueProperties()),
-        m_target(target), m_got_host_env(false) {}
+  TargetOptionValueProperties(const TargetPropertiesSP &target_properties_sp)
+      : OptionValueProperties(*target_properties_sp->GetValueProperties()) {}
 
   const Property *GetPropertyAtIndex(const ExecutionContext *exe_ctx,
                                      bool will_modify,
@@ -3374,9 +3371,6 @@
     // When getting the value for a key from the target options, we will always
     // try and grab the setting from the current target if there is one. Else
     // we just use the one from this instance.
-    if (idx == ePropertyEnvVars)
-      GetHostEnvironmentIfNeeded();
-
     if (exe_ctx) {
       Target *target = exe_ctx->GetTargetPtr();
       if (target) {
@@ -3389,41 +3383,6 @@
     }
     return ProtectedGetPropertyAtIndex(idx);
   }
-
-  lldb::TargetSP GetTargetSP() { return m_target->shared_from_this(); }
-
-protected:
-  void GetHostEnvironmentIfNeeded() const {
-    if (!m_got_host_env) {
-      if (m_target) {
-        m_got_host_env = true;
-        const uint32_t idx = ePropertyInheritEnv;
-        if (GetPropertyAtIndexAsBoolean(
-                nullptr, idx, g_target_properties[idx].default_uint_value != 0)) {
-          PlatformSP platform_sp(m_target->GetPlatform());
-          if (platform_sp) {
-            Environment env = platform_sp->GetEnvironment();
-            OptionValueDictionary *env_dict =
-                GetPropertyAtIndexAsOptionValueDictionary(nullptr,
-                                                          ePropertyEnvVars);
-            if (env_dict) {
-              const bool can_replace = false;
-              for (const auto &KV : env) {
-                // Don't allow existing keys to be replaced with ones we get
-                // from the platform environment
-                env_dict->SetValueForKey(
-                    ConstString(KV.first()),
-                    OptionValueSP(new OptionValueString(KV.second.c_str())),
-                    can_replace);
-              }
-            }
-          }
-        }
-      }
-    }
-  }
-  Target *m_target;
-  mutable bool m_got_host_env;
 };
 
 // TargetProperties
@@ -3450,10 +3409,10 @@
 
 // TargetProperties
 TargetProperties::TargetProperties(Target *target)
-    : Properties(), m_launch_info() {
+    : Properties(), m_launch_info(), m_target(target) {
   if (target) {
     m_collection_sp = std::make_shared<TargetOptionValueProperties>(
-        target, Target::GetGlobalProperties());
+        Target::GetGlobalProperties());
 
     // Set callbacks to update launch_info whenever "settins set" updated any
     // of these properties
@@ -3463,6 +3422,8 @@
         ePropertyRunArgs, [this] { RunArgsValueChangedCallback(); });
     m_collection_sp->SetValueChangedCallback(
         ePropertyEnvVars, [this] { EnvVarsValueChangedCallback(); });
+    m_collection_sp->SetValueChangedCallback(
+        ePropertyInheritEnv, [this] { EnvVarsValueChangedCallback(); });
     m_collection_sp->SetValueChangedCallback(
         ePropertyInputPath, [this] { InputPathValueChangedCallback(); });
     m_collection_sp->SetValueChangedCallback(
@@ -3642,19 +3603,43 @@
   m_launch_info.GetArguments() = args;
 }
 
+Environment TargetProperties::ComputeEnvironment() const {
+  Environment env;
+
+  if (m_target &&
+      m_collection_sp->GetPropertyAtIndexAsBoolean(
+          nullptr, ePropertyInheritEnv,
+          g_target_properties[ePropertyInheritEnv].default_uint_value != 0)) {
+    if (auto platform_sp = m_target->GetPlatform()) {
+      Environment platform_env = platform_sp->GetEnvironment();
+      for (const auto &KV : platform_env)
+        env[KV.first()] = KV.second;
+    }
+  }
+
+  Args property_env;
+  m_collection_sp->GetPropertyAtIndexAsArgs(nullptr, ePropertyEnvVars,
+                                            property_env);
+  for (const auto &KV : Environment(property_env))
+    env[KV.first()] = KV.second;
+
+  Args property_unset_env;
+  m_collection_sp->GetPropertyAtIndexAsArgs(nullptr, ePropertyUnsetEnvVars,
+                                            property_env);
+  for (const auto &var : property_unset_env)
+    env.erase(var.ref());
+
+  return env;
+}
+
 Environment TargetProperties::GetEnvironment() const {
-  // TODO: Get rid of the Args intermediate step
-  Args env;
-  const uint32_t idx = ePropertyEnvVars;
-  m_collection_sp->GetPropertyAtIndexAsArgs(nullptr, idx, env);
-  return Environment(env);
+  return ComputeEnvironment();
 }
 
 void TargetProperties::SetEnvironment(Environment env) {
   // TODO: Get rid of the Args intermediate step
   const uint32_t idx = ePropertyEnvVars;
   m_collection_sp->SetPropertyAtIndexFromArgs(nullptr, idx, Args(env));
-  m_launch_info.GetEnvironment() = std::move(env);
 }
 
 bool TargetProperties::GetSkipPrologue() const {
@@ -3972,7 +3957,7 @@
 }
 
 void TargetProperties::EnvVarsValueChangedCallback() {
-  m_launch_info.GetEnvironment() = GetEnvironment();
+  m_launch_info.GetEnvironment() = ComputeEnvironment();
 }
 
 void TargetProperties::InputPathValueChangedCallback() {
diff --git a/lldb/source/Target/TargetProperties.td b/lldb/source/Target/TargetProperties.td
--- a/lldb/source/Target/TargetProperties.td
+++ b/lldb/source/Target/TargetProperties.td
@@ -81,6 +81,9 @@
   def EnvVars: Property<"env-vars", "Dictionary">,
     DefaultUnsignedValue<16>,
     Desc<"A list of all the environment variables to be passed to the executable's environment, and their values.">;
+  def UnsetEnvVars: Property<"unset-env-vars", "Array">,
+    DefaultUnsignedValue<16>,
+    Desc<"A list of environment variable names to be unset in the inferior's environment.">;
   def InheritEnv: Property<"inherit-env", "Boolean">,
     DefaultTrue,
     Desc<"Inherit the environment from the process that is running LLDB.">;